Low field magnetic resonance imaging methods and apparatus

ABSTRACT

According to some aspects, a laminate panel is provided. The laminate panel comprises at least one laminate layer including at least one non-conductive layer and at least one conductive layer patterned to form at least a portion of a B0 coil configured to contribute to a B0 field suitable for use in low-field magnetic resonance imaging (MRI).

RELATED APPLICATIONS

This application claims benefit under 35 U.S.C. § 120 and is acontinuation application of U.S. application Ser. No. 15/721,340,entitled “LOW FIELD MAGNETIC RESONANCE IMAGING METHODS AND APPARATUS,”filed on Sep. 29, 2017, which claims benefit under 35 U.S.C. § 120 andis a continuation application of U.S. application Ser. No. 14/845,652,entitled “LOW FIELD MAGNETIC RESONANCE IMAGING METHODS AND APPARATUS,”filed on Sep. 4, 2015, which claims priority under 35 U.S.C. § 119(e) toU.S. Provisional Patent Application Ser. No. 62/046,814, filed Sep. 5,2014 and entitled “Low Field Magnetic Resonance Imaging Methods andApparatus,” U.S. Provisional Patent Application Ser. No. 62/111,320,filed Feb. 3, 2015 and entitled “Thermal Management Methods andApparatus,” U.S. Provisional Patent Application Ser. No. 62/110,049,filed Jan. 30, 2015 and entitled “Noise Suppression Methods andApparatus,” and U.S. Provisional Patent Application Ser. No. 62/174,666,filed Jun. 12, 2015 and entitled “Automatic Configuration of a Low FieldMagnetic Resonance Imaging System,” each of the above applications ofwhich is herein incorporated by reference in its entirety.

BACKGROUND

Magnetic resonance imaging (MRI) provides an important imaging modalityfor numerous applications and is widely utilized in clinical andresearch settings to produce images of the inside of the human body. Asa generality, MRI is based on detecting magnetic resonance (MR) signals,which are electromagnetic waves emitted by atoms in response to statechanges resulting from applied electromagnetic fields. For example,nuclear magnetic resonance (NMR) techniques involve detecting MR signalsemitted from the nuclei of excited atoms upon the re-alignment orrelaxation of the nuclear spin of atoms in an object being imaged (e.g.,atoms in the tissue of the human body). Detected MR signals may beprocessed to produce images, which in the context of medicalapplications, allows for the investigation of internal structures and/orbiological processes within the body for diagnostic, therapeutic and/orresearch purposes.

MRI provides an attractive imaging modality for biological imaging dueto the ability to produce non-invasive images having relatively highresolution and contrast without the safety concerns of other modalities(e.g., without needing to expose the subject to ionizing radiation,e.g., x-rays, or introducing radioactive material to the body).Additionally, MRI is particularly well suited to provide soft tissuecontrast, which can be exploited to image subject matter that otherimaging modalities are incapable of satisfactorily imaging. Moreover, MRtechniques are capable of capturing information about structures and/orbiological processes that other modalities are incapable of acquiring.However, there are a number of drawbacks to conventional MRI techniquesthat, for a given imaging application, may include the relatively highcost of the equipment, limited availability (e.g., difficulty andexpense in gaining access to clinical MRI scanners), the length of theimage acquisition process, etc.

The trend in clinical MRI has been to increase the field strength of MRIscanners to improve one or more of scan time, image resolution, andimage contrast, which in turn drives up costs of MRI imaging. The vastmajority of installed MRI scanners operate using at least at 1.5 or 3tesla (T), which refers to the field strength of the main magnetic fieldB0 of the scanner. A rough cost estimate for a clinical MRI scanner ison the order of one million dollars per tesla, which does not evenfactor in the substantial operation, service, and maintenance costsinvolved in operating such MRI scanners.

Additionally, conventional high-field MRI systems typically requirelarge superconducting magnets and associated electronics to generate astrong uniform static magnetic field (B0) in which a subject (e.g., apatient) is imaged. Superconducting magnets further require cryogenicequipment to keep the conductors in a superconducting state. The size ofsuch systems is considerable with a typical MRI installment includingmultiple rooms for the magnetic components, electronics, thermalmanagement system, and control console areas, including a speciallyshielded room to isolate the magnetic components of the MRI system. Thesize and expense of MRI systems generally limits their usage tofacilities, such as hospitals and academic research centers, which havesufficient space and resources to purchase and maintain them. The highcost and substantial space requirements of high-field MRI systemsresults in limited availability of MRI scanners. As such, there arefrequently clinical situations in which an MRI scan would be beneficial,but is impractical or impossible due to the above-described limitationsand as discussed in further detail below.

SUMMARY

The inventors have appreciated that laminate techniques may be utilizedto produce a laminate panel having one or more magnetic components, orportions thereof, fabricated therein. Such a laminate panel can be usedalone, in combination with one or more additional laminate panels and/orin combination with other magnetic components to facilitate providingmagnetic field(s) for use in magnetic resonance imaging (MRI). Someembodiments include a laminate panel comprising at least one laminatelayer including at least one non-conductive layer and at least oneconductive layer patterned to form at least a portion of a B₀ coilconfigured to contribute to a B₀ field suitable for use in low-fieldMRI.

Some embodiments include a hybrid magnetic component comprising at leastone B₀ coil formed by a wound conductor and configured to contribute toa B₀ field suitable for use in low-field magnetic resonance imaging, andat least one laminate panel comprising a plurality of laminate layershaving patterned thereon at least one B₀ coil, or a portion thereof,and/or at least one gradient coil or a portion thereof.

Some embodiments include a method of manufacturing a laminate panel of alow-field magnetic resonance imaging system, the method comprisingproviding at least one non-conductive layer, providing at least oneconductive layer, attaching the at least one non-conductive layer andthe at least one conductive layer to form at least one laminate layer,and patterning at least one conductive layer to form at least a portionof a B₀ coil configured to contribute to a B₀ field suitable for use inlow-field magnetic resonance imaging (MRI).

Some embodiments include a low-field magnetic resonance imaging (MRI)system, comprising a first laminate panel having at least one firstmagnetic component formed thereon, a second laminate panel having atleast one second magnetic component formed thereon, and at least onepower source configured to provide power to operate the at least onefirst magnetic component and the at least one second magnetic component,wherein the at least one first magnetic component and the at least onesecond magnetic component, when operated, generate at least one magneticfield suitable for low-field MRI.

BRIEF DESCRIPTION OF THE DRAWINGS

Various aspects and embodiments of the disclosed technology will bedescribed with reference to the following figures. It should beappreciated that the figures are not necessarily drawn to scale.

FIG. 1 is a schematic illustration of a low-field MRI system using abi-planar magnet configuration;

FIGS. 2A-2C are schematic illustrations of single-layer and amulti-layer laminate techniques for producing a laminate panel, inaccordance with some embodiments;

FIG. 3A illustrates an example portion of a laminate layer using copperas the material for the conductive traces patterned thereon;

FIG. 3B illustrates an example portion of a laminate layer usingaluminum as the material for the conductive traces patterned thereon;

FIG. 4 shows an exploded view of example magnetic components of alow-field MRI system formed on layers of a multi-layer laminate panel,in accordance with some embodiments;

FIG. 5 illustrates exemplary layers of a laminate panel integrating a B₀magnet, in accordance with some embodiments;

FIGS. 6A and 6B illustrate an exemplary techniques for patterningmultiple coils on a laminate layer of a laminate panel, in accordancewith some embodiments;

FIGS. 7A-7C show spiral designs for a B₀ coil formed on at least onelayer of a multilayer laminate panel in accordance with someembodiments;

FIGS. 8A-8C show circular designs for a B₀ coil formed on at least onelayer of a multilayer laminate panel, in accordance with someembodiments;

FIG. 9A-9C illustrate exemplary configurations for an x-gradient, ay-gradient coil and a z-gradient coil, respectively, in accordance withsome embodiments;

FIG. 10 illustrates exemplary layers of a laminate panel integrating aB₀ magnet and gradient coils, in accordance with some embodiments;

FIGS. 11A and 11B illustrate exemplary shim coils that may be fabricatedusing lamination techniques discussed herein, in accordance with someembodiments;

FIG. 12 shows a solenoid-based coil configuration for laminate panelsformed using techniques described herein, in accordance with someembodiments;

FIG. 13 shows a block diagram of exemplary components of a low-field MRIsystem, in accordance with some embodiments;

FIGS. 14A-14D illustrate hybrid designs for a B₀ magnet in accordancewith some embodiments;

FIGS. 15A-15C illustrate exemplary configurations for laminate panelsformed using techniques described herein, in accordance with someembodiments;

FIG. 16 is a schematic block diagram of components of a low-field MRIsystem, in accordance with some embodiments;

FIG. 17 illustrates a thermal management component, in accordance withsome embodiments;

FIG. 18 is a block diagram of an RF signal chain for use with someembodiments;

FIGS. 19A and 19B illustrate a seated system configuration of alow-field MRI system using laminate panels, in accordance with someembodiments;

FIGS. 20A-20C illustrate a reclining system configuration of a low-fieldMRI system using laminate panels, in accordance with some embodiments;

FIGS. 21A-21G illustrates portable transformable system configurationsof a low-field MRI system using laminate panels, in accordance with someembodiments; and

FIGS. 22A-22C illustrate exemplary helmets incorporating low field MRImagnetic components, in accordance with some embodiments.

DETAILED DESCRIPTION

The MRI scanner market is overwhelmingly dominated by high-fieldsystems, and is exclusively so for medical or clinical MRI applications.As discussed above, the general trend in medical imaging has been toproduce MRI scanners with increasingly greater field strengths, with thevast majority of clinical MRI scanners operating at 1.5 T or 3 T, withhigher field strengths of 7 T and 9 T used in research settings. As usedherein, “high-field” refers generally to MRI systems presently in use ina clinical setting and, more particularly, to MRI systems operating witha main magnetic field (i.e., a B₀ field) at or above 1.5 T, thoughclinical systems operating between 0.5 T and 1.5 T are generally alsoconsidered “high-field.” By contrast, “low-field” refers generally toMRI systems operating with a B₀ field of less than or equal toapproximately 0.2 T.

The appeal of high-field MRI systems include improved resolution and/orreduced scan times compared to lower field systems, motivating the pushfor higher and higher field strengths for clinical and medical MRIapplications. However, as discussed above, increasing the field strengthof MRI systems yields increasingly more expensive and complex MRIscanners, thus limiting availability and preventing their use as ageneral purpose and/or generally available imaging solution. Asdiscussed above, contributing factors to the high cost of high-field MRIare expensive superconducting wires and the cryogenic cooling systemsneeded to keep the wires in a superconducting state. For example, the B0magnet for high field MRI systems frequently employ superconducting wirethat is not only itself expensive, but requires expensive andcomplicated cryogenic equipment to maintain the superconducting state.

Low-field MR has been explored in limited contexts for non-imagingresearch purposes and narrow and specific contrast-enhanced imagingapplications, but is conventionally regarded as being unsuitable forproducing clinically-useful images. For example, the resolution,contrast, and/or image acquisition time is generally not regarded asbeing suitable for clinical purposes such as, but not limited to, tissuedifferentiation, blood flow or perfusion imaging, diffusion-weighted(DW) or diffusion tensor (DT) imaging, functional MRI (fMRI), etc.

The inventors have developed techniques for producing improved quality,portable and/or lower-cost low-field MRI systems that can improve thewide-scale deployability of MRI technology in a variety of environmentsbeyond the large MRI installments at hospitals and research facilities.Some aspects of the inventors' contribution derive from theirrecognition that a significant factor contributing to the cost andcomplexity of both high-field and low-field MRI is the magneticscomponents needed to produce MR signals that are useable for imagingapplications.

Briefly, MRI involves placing an object (e.g., all or a portion of apatient) to be imaged in a static, homogenous magnetic field B₀ to alignatomic spins of atoms in the direction of the B₀ field. For high-fieldMRI systems, superconducting magnets made from coils of superconductingwire are generally required to achieve the homogeneity of B₀ at fieldstrengths employed in high-field MRI. Not only are the superconductingmagnets themselves costly, but they generally require cryogenic coolingduring operation, increasing the cost and complexity of high-field MRIscanners. In addition to the B₀ magnetic component, gradient coils areprovided to spatially encode MR signals from the object, and transmitand receive coils are provided to generate a magnetic field Bi at afrequency related to the field strength of the magnetic field B₀ tocause atomic spins to change orientation and to detect MR signalsemitted from the object upon realignment of the atomic spins with themagnetic field B₀, respectively. At high-field strengths and theassociated high frequencies, these magnetic components are alsorelatively complex and expensive.

The inventor(s) have appreciated that low-field MRI systems do notrequire expensive superconducting magnets and/or the associatedcryogenic cooling systems, and the reduced field strengths mayfacilitate reduction in the complexity and/or expense of other magneticcomponents in the system. To this end, some embodiments are directed tolow-field MRI systems having substantially less complex and expensivemagnetic components, as discussed in further detail below. However,producing such magnetic components and manufacturing a system suitablefor performing low-field MRI using conventional techniques for doing so,while significantly less complex and expensive than high-field MRI,still may present technical challenges that increase complexity andexpense. For example, constructing B₀ magnets using conventionaltechniques typically requires winding significant amounts of high-gradecopper wire about a frame according to precise design specifications toproduce coils capable of generating a magnetic field of satisfactoryhomogeneity at a desired field strength, a process which is relativelytime consuming, expensive, susceptible to production deviation, and thatgenerally does not scale well. Further issues arise with alignment ofthe B₀ magnets and alignment with other magnetic components, asdiscussed in further detail below.

The inventor(s) have recognized that laminate techniques, similar insome respects to those utilized in producing printed circuit boards, maybe employed to fabricate one or more (or a portion of one or more)magnetic components of a low-field MRI scanner. According to someembodiments, one or more magnetic components (or portion thereof) foruse in low-field MRI is provided as a laminate panel comprising one ormore non-conductive layers and one or more conductive layers patternedto form the one or more magnetic components or portion thereof. The term“laminate” refers herein to a plurality of superposed layers, typicallyinvolving at least one or more non-conductive layers and one or moreconductive layers. Unless otherwise specified, the term “laminate” isgeneric to the types of materials used and indicates the affixing ofmultiple layers together, but does not specify any particular type ofmaterial or arrangement of materials used to produce the layers. Theterm “panel” generally describes a structure resulting from a laminateof multiple laminate layers and can be of any shape or size, and caninclude any number of layers.

According to some embodiments, one or more B₀ coils, one or moregradient coils, one or more transmit/receive coils, and/or one or moreshim coils, or any desired portions or combinations thereof may befabricated on a single laminate panel or distributed between multiplelaminate panels, as discussed in further detail below. Utilizinglaminate techniques may facilitate a cost-effective, scalable, flexible,repeatable and/or customizable approach to producing low-field MRImagnetics. Furthermore, the inventors have appreciated that theprecision achievable using laminate techniques allows for the design andmanufacture of geometries, configurations and arrangements that are notpossible using conventional techniques for manufacturing or producingthe magnetics of an MRI system.

Following below are more detailed descriptions of various conceptsrelated to, and embodiments of, methods and apparatus for low fieldmagnetic resonance applications including low-field MRI. It should beappreciated that various aspects described herein may be implemented inany of numerous ways. Examples of specific implementations are providedherein for illustrative purposes only. In addition, the various aspectsdescribed in the embodiments below may be used alone or in anycombination, and are not limited to the combinations explicitlydescribed herein.

As discussed above, the inventor(s) have developed low-field MRI systemsthat address one or more of the problems associated with high-field MRIsystems. For example, exemplary low-field MRI systems may be implementedwithout using superconducting magnets and consequently without theassociated cryogenic cooling apparatus, thereby significantly reducingthe cost, complexity and size of the resulting MRI system. To produce aB₀ field having a magnetic field strength and magnetic field homogeneitysuitable for high-field MRI, a solenoid coil formed of superconductingmaterial is used wherein the B₀ field generated is in the direction ofthe axis through the center of the solenoid. As a result, imaging apatient requires placing the patient inside the solenoid coil. While thesolenoid coil is particularly well-suited for generating a homogenousfield at high field strengths, this geometry not only increases the sizeof equipment, but requires that a patient be inserted into a cylindricalbore to be imaged. Thus, this geometry may be unsuitable for patientswith claustrophobia and may be incapable of accommodating largepatients. Thus, the solenoid coil geometry generally required to producea suitable B₀ magnet for high-field MRI has further limitations thatprevent high-field MRI from being a practical and available generalpurpose imager.

The inventors have appreciated that characteristics of low-field MRIpermit alternate coil geometries not suitable for high-field MRI to beused to generate a B₀ field suitable for low-field MRI. FIG. 1schematically illustrates a portion of a low-field MRI system 100including a bi-planar magnet geometry that may be utilized to generate aB₀ field suitable for low-field MRI imaging, in accordance with someembodiments. The bi-planar magnet comprises two outer coils 110 a and110 b and two inner coils 112 a and 112 b. When appropriate current isapplied to the coils, a magnetic field is generated in the directionindicated by the arrow to produce a B₀ field having a field of viewbetween the coils that, when designed and constructed appropriately, maybe suitable for low-field MRI.

It should be appreciated that the bi-planar geometry illustrated in FIG.1 is generally unsuitable for high-field MRI due to the difficulty inobtaining a B₀ field of sufficient homogeneity for high-field MRI. Thebi-planar B₀ magnet illustrated in FIG. 1 provides a generally opengeometry, facilitating its use with patients who suffer fromclaustrophobia that may refuse to be imaged with conventional high-fieldsolenoid coil geometries. Furthermore, the bi-planar design mayfacilitate its use with larger patients as a result of its open designand, in some instances, a generally larger field of view possible atlow-field strengths and homogeneities.

However, while the bi-planar B₀ magnet illustrated in FIG. 1 provides amuch less complex and lower cost B₀ magnet then what is possible forhigh-field MRI, production of coils 110 a, 110 b, 112 a and 112 b istypically a relatively time-consuming and sensitive process thatgenerally involves the repeated winding of copper wire around a supportframe to produce a number of turns in accordance with a specific designfor a given set of coils. To produce a suitable B₀ field for low-fieldMRI, a generally high-quality conductor (e.g., thick copper wire withhigh grade insulation) is often used to support the relatively largecurrent required to generate the desired B₀ field. Care must be taken toensure that each turn of the conductor is wound precisely and properlyaligned to generate a B₀ field having a desired homogeneity. Asindicated in FIG. 1, an exemplary diameter of the outer coils in abi-planar magnet may be 220 cm with a typical number of turns being onthe order of 50 turns or more, thereby requiring a substantial amount ofconductor material (e.g., more than a kilometer of generally high gradewire for each side of the bi-planar magnet) that must be precisely woundin alignment over numerous turns.

Additionally, each coil in a pair (e.g., coils 110 a, 110 b and coils112 a, 112 b) should be manufactured to be substantially identical toits corresponding coil in the pair to avoid degrading the homogeneity ofthe resulting B₀ field once the coils are energized. Moreover, the coilson each side (e.g., coils 110 a, 112 a and coils 110 b, 112 b) of thebi-planar magnet must also be carefully positioned and aligned to reduceinhomogeneity in the resulting B₀ field. Accordingly, manufacturing andinstalling such coils to produce a sufficiently homogeneous B₀ field forlow-field MRI using conventional construction techniques tends to berelatively costly, time intensive and prone to error.

As discussed above, the inventor(s) have recognized that laminatetechniques may be utilized to fabricate a B₀ magnet or portion thereoffor use in low-field MRI in place of (or in combination with) theconventional manufacturing techniques described above. In particular,the inventors have appreciated and understood that the low-fieldcharacteristics of the B₀ magnetic component allows for fabrication ofthe B₀ magnetic component, or a portion thereof, using techniquespreviously unavailable for producing a B₀ magnet for MRI. For example,among other reasons, the inventors have appreciated that the lower powerrequirements and/or reduced thermal output of low-field MRI allows forproduction of magnetic components using laminate techniques, which werenot available in the high-field context.

According to some embodiments, a laminate panel comprises at least oneconductive layer patterned to form one or more B₀ coils, or a portion ofone or more B₀ coils, capable of producing or contributing to a B₀magnetic field suitable for low-field MRI. As used herein, a B₀ coilrefers herein to any coil that provides or contributes to a B₀ magneticfield and may include one or more main B₀ coils, or portions thereof,one or more shim coils, or portions thereof, one or more correctioncoils, or portions thereof, etc.

A laminate panel may comprise a plurality of concentric coils to formone “side” of the pair of bi-planar B₀ coils illustrated FIG. 1. Asecond laminate panel may be similarly constructed to incorporate B₀coils for the other “side” of the field of view in the bi-planar design.In this manner, magnetic components used to generate a B₀ field for alow-field MRI system may be constructed using laminate panel techniques.

As discussed in further detail below, using laminate techniques tofabricate one or more B₀ coils (or a portion thereof) can address one ormore of the drawbacks discussed above in manufacturing a B₀ magnet foruse in low field MRI. For example, B₀ field homogeneity is quitesensitive to relatively small changes in the parameters of therespective coils. In particular, small variations in the coil windings,position and alignment of the various coils, etc., result in fieldinhomogeneity of the B₀ field produced. As a result, it may therefore bedifficult to produce a B₀ magnet capable of generating a B₀ field withfield homogeneity suitable for performing low field MRI in a generallyrepeatable and low cost process. In particular, reproducing such a B₀magnet may be difficult as conventional manufacturing techniques do notlend themselves to repeatable, reliable production and therefore do notscale well, limiting the ability to produce numerous satisfactory B₀magnets in a time and/or cost efficient manner. Laminate techniques arecapable of producing magnetic components much more precisely andaccurately than what is feasible using conventional techniques,facilitating a flexible, repeatable, and highly scalable technique forproducing magnetic components, as discussed in further detail below.

FIG. 1 also schematically illustrates a pair of planar gradient coilsets 120 a, 120 b to generate magnetic fields to facilitate phase andfrequency encoding for the portion of the low-field MRI systemillustrated. As discussed above, MRI systems encode received MR signalsby systematically varying the B₀ field in a known manner using gradientcoils to encode the spatial location of received MR signals as afunction of frequency or phase. For example, gradient coils may beconfigured to vary frequency or phase as a linear function of spatiallocation along a particular direction, although more complex spatialencoding profiles may also be provided by using nonlinear gradientcoils. For example, a first gradient coil may be configured toselectively vary the B₀ field in a first (X) direction to performfrequency encoding in that direction, a second gradient coil may beconfigured to selectively vary the B₀ field in a second (Y) directionsubstantially orthogonal to the first direction to perform phaseencoding, and a third gradient coil may be configured to selectivelyvary the B₀ field in a third (Z) direction substantially orthogonal tothe first and second directions to enable slice selection for volumetricimaging applications.

Gradient coils are designed to operate with a specific B₀ magneticcomponent (e.g., one or more B₀ coils as shown in FIG. 1) and, tooperate satisfactorily, typically require relatively precise manufactureand subsequent alignment with the B₀ magnetic component. The inventorshave recognized that using laminate techniques to fabricate one or moregradient coils (or portions thereof) may facilitate a simpler more costeffective approach to manufacturing magnetics components of a low fieldMRI system.

According to some embodiments, a laminate panel comprises at least oneconductive layer patterned to form one or more gradient coils, or aportion of one or more gradient coils, capable of producing orcontributing to magnetic fields suitable for providing spatial encodingof detected MR signals when operated in a low-field MRI apparatus. Forexample, the laminate panel may comprise one or more conductive layerspatterned to form one or more X-gradient coils (or portions thereof),one or more Y-gradient coils (or portions thereof) and/or one or moreZ-gradient coils (or portions thereof). The laminate panel forming oneor more gradient coils (or portions thereof) may be separate from acorresponding B₀ magnetic component, or may be formed in one or morelayers of a same laminate panel. With respect to the latter, the one ormore gradient coils may be formed by conductive layers shared with (butelectrically isolated from) the one or more B₀ coils (or portionsthereof) or may be formed in one or more conductive layers separate fromthe one or more B₀ coils (or portions thereof). Integration of one ormore gradient coils (or portions thereof) with one or more B₀ coils (orportions thereof) in a laminate panel may facilitate a simpler moreflexible approach to designing and manufacturing magnetic components forlow-field MRI, further aspects of which are discussed below.

As discussed above, MRI systems stimulate and detect emitted MR signalsusing transmit and receive coils, respectively (often referred to asradio frequency (RF) coils). The configuration of the transmit/receivecoils varies with implementation and may include a single coil for bothtransmitting and receiving, separate coils for transmitting andreceiving, multiple coils for transmitting and/or receiving, or anycombination to achieve single channel or parallel MRI systems. Thus, thetransmit/receive magnetic component is often referred to as Tx/Rx orTx/Rx coils to generically refer to the various configurations for thetransmit and receive component of an MRI system.

The inventors have recognized that laminate techniques may also be usedto fabricate one or more transmit/receive coils in a low field MRIsystem. According to some embodiments, a laminate panel comprises atleast one conductive layer patterned to form one or more transmit and/orreceive coils, or a portion of one or more transmit and/or receivecoils, configured to stimulate an MR response by producing a Biexcitation field (transmit) and/or receive an emitted MR signal(receive) when operated in conjunction with magnetic componentsconfigured to produce a B₀ field and/or corresponding gradient fieldsfor spatially encoding received MR signals. Such a laminate panel mayincorporate single transmit and/or receive coils (or portions thereof)or multiple transmit and/or receive coils (or portions thereof) forperforming single channel or parallel MRI, respectively, and may beformed in a separate laminate panel or integrated in a laminate panelcontaining one or more B₀ coils (or portions thereof) and/or one or moregradient coils (or portions thereof), as discussed in further detailbelow.

A low field MRI system may further include additional magneticcomponents such as one or more shim coils arranged to generate magneticfields in support of the system to, for example, increase the strengthand/or homogeneity of the B₀ field, counteract deleterious field effectssuch as those created by operation of the gradient coils, loadingeffects of the object being imaged, or to otherwise support themagnetics of the low field MRI system. When a shim coil is operated tocontribute to the B₀ field of an MRI system (e.g., to contribute to thefield strength and/or to improve homogeneity), the shim coil functionsas a B₀ coil of the system and should be understood as such. In someimplementations, one or more shim coils may be operated independently ofother B₀ coils of the system, as discussed in further detail below.

Furthermore, a low field MRI system may further include shieldingcomponent(s) arranged to suppress unwanted electromagnetic radiation inthe environment and/or between components. The inventor(s) haverecognized that laminate techniques may be utilized to fabricate suchcomponents, for example, one or more shim coils (or portions thereof)and/or one or more shielding components, either by forming suchcomponents in separate laminate panel(s) or integrating such componentsin a laminate panel containing any one or combination of other magneticcomponents (or portions thereof) of a low field MRI system, as discussedin further detail below.

As discussed above, laminate techniques for producing panels, plates, or“boards” containing one or more magnetic components of a low field MRIsystem may resemble, in principle, techniques conventionally used tofabricate printed circuit boards (PCBs) and certain limited printedelectronics, though different in scale, power and thermal requirements,etc. Such laminate techniques generally involve forming non-conductiveand conductive layers of material and patterning the conductive and/ornon-conductive layer(s) (e.g., by selectively removing and/or addingmaterial) to produce a desired conducting pattern or “circuit.” Suchtechniques are conventionally used to produce single-layer andmulti-layer PCBs, for example, to provide electrical interconnectionbetween discrete components mounted on the surface of the PCB, and havealso been used to a limited extent to produce certain electroniccomponents.

As discussed above, due to the high field strengths, significant powerrequirements, complex cryogenic cooling systems, etc., of high field MRIsystems, laminate techniques do not present a viable solution in thehigh field context and have not been previously contemplated for use inproducing magnetic components for MRI. However, the inventor(s) haverecognized that, in the low field context, laminate techniques may beused to fabricate one or more magnetic components of a low field MRIsystem, examples of which are discussed in further detail below.

As also discussed above, producing a B₀ magnet using conventionaltechniques (e.g., one or more wound coils) can be a time consumingprocess and may be susceptible to alignment errors and/or inhomogeneitydue to manufacturing deviation, etc. However, the inventors haveappreciated that such conventional techniques for producing magneticcomponents may be advantageously used in conjunction with laminatetechniques described herein. For example, one or more B₀ coilsmanufactured using conventional techniques may be supplemented with oneor more B₀ coils fabricated using laminate techniques. Some examples of“hybrid” magnets are discussed in further detail below.

FIG. 2A schematically illustrates a laminate panel 200 that includes asingle non-conductive layer 210 and a single conductive layer 212 formedon the non-conductive layer. The non-conductive layer 210 (also referredto herein as a substrate) may be formed from any suitable material. Forexample, substrate 210 may be formed from any one or combination ofsuitable core materials, composites, adhesives and/or laminates may beutilized to form non-conductive layers and facilitate producing alaminate panel, including, but not limited to, FR4, ceramic, plastic,glass, polymide, epoxy, pre-impregnated composite fibers (pre-preg),multifunctional epoxy laminates such as 92 ML, or any other material(s)or combinations thereof having suitable properties. Substrate 210 may bea single layer or constructed of multiple layers of non-conductivematerial, each layer of which may be made from a same or differentnon-conductive material. Layering the substrate may allow forconstruction of a substrate that utilizes beneficial properties ofdifferent materials. Substrate 210 may be constructed to any desireddimensions, having length, width and thickness suitable for a givendesign.

Likewise, conductive layer 212 may be formed from any suitableconducting material. For example, conductive layer 212 may be a thin orthick film of copper or other suitable conductive material, a thick orextremely thick conductive layer (e.g., “extreme copper”), conductiveplate, or any other type of conductive layer capable of being formed asa laminate on non-conductive substrate 210 by any suitable technique orprocess (e.g., via dip coating, electroplating, printing, molding,bonding, vacuum impregnating, pressing, dry adhesive, or any othersuitable technique(s)). According to some embodiments, aluminum may beused as a conductor to take advantage of associated cost and weightreductions, as discussed in further detail below.

To produce desired “circuitry,” conductive layer(s) 212 may be patternedto form electrical conductors for desired portions of one or moremagnetic components of a low-field MRI apparatus using any one orcombination of various subtractive, additive and/or semi-additiveprocesses. Subtractive processes selectively remove the conductivematerial (e.g., copper) from the conductive layer leaving a desiredconductive pattern providing a desired conducting circuit or portion ofa circuit using, for example, any of various lithographic processesincluding, but not limited to, chemical etching, photoengraving, etc.Such processes are performed by providing a resist material in thedesired pattern (often referred to as a mask) and introducing theconductive layer to the corresponding etchant to remove the conductivematerial in locations not treated with the resist material. Anothersubtractive process involves milling away unwanted portions of theconductive layer leaving the desired conductive pattern. The subtractiveprocesses described herein and/or any other suitable process may be usedalone or in any combination to fabricate the desired conductive pattern.

Additive processes may involve electroplating the desired conductivepattern on the substrate or “printing” the pattern using a conductiveink. For example, electroplating may involve exposing photosensitivefilm masked in a desired pattern. The exposed pattern may then beintroduced to a chemical bath to allow the pattern to be capable ofmetal ion bonding and then plated with a conductor (e.g., with copper)that bonds with the pattern sensitized in the chemical bath to form thedesired conductive pattern. Additive processes have the advantage thatless conductive material is needed to form the desired conductivepattern than subtractive techniques. Other processes combine bothsubtractive and additive techniques to form the desired conductivepattern.

According to some embodiments, one or more magnetic componentsfabricated using laminate techniques may require conductive layers to befabricated at relatively large thicknesses, often referred to as “heavycopper,” (e.g., 5 oz/ft²-19 oz/ft²) or “extreme copper,” (e.g., 20oz/ft²-200 oz/ft²), though the techniques apply regardless of the choiceof conductor material. Examples of suitable techniques for patterningheavy or extreme copper include, but are not limited to, any one orcombination of cupric chloride etch, ferric chloride etch, mechanicalmilling, plasma etch, laser etch, electro-discharge-machining (EDM),plating up, etc. It should be appreciated that any single technique orcombination of techniques described herein may be utilized, or any othertechnique suitable for patterning a conductive layer on a non-conductivesubstrate and/or for producing a laminate panel may be used, as aspectsof forming one or more magnetic components (or portions thereof) of alow field MRI system in a laminate panel are not limited to anyparticular technique or combination of techniques for doing so.

FIG. 2B schematically illustrates a laminate panel 205 that includes aplurality of non-conductive layers 210 and a plurality of conductivelayers 212 formed between the non-conductive layers. Connections betweenthe conductive layers 212 may be achieved by forming holes filled with aconductive material (e.g., plated through-holes) in the interveningnon-conductive layers called “vias,” as described in more detail below.Although only two non-conductive layers and two conductive layers areexplicitly illustrated in FIG. 2B, as indicated by the ellipses, anynumber of non-conductive layers and conductive layers may be used toachieve a laminate panel according to a desired design, some examples ofwhich are described in further detail below.

Additionally, it should be appreciated that multiple conductive layersmay be provided for each non-conductive layer, for example, anon-conductive layer having a conductive layer laminated to both sides.FIG. 2C illustrates a multi-layer panel formed by attaching together twolaminate layers, each having a non-conductive layer 210 with aconductive layer laminated to both sides of the respectivenon-conductive layer. The multi-layer laminates may be attached usingone or more adhesive layers 214. Adhesive layer(s) 214 may be anysuitable adhesive or combination of materials such as pre-preg, dryadhesive, epoxy and/or any other suitable layer or combination of layersthat, when activated (e.g., via heat and/or pressure) bonds themulti-layer laminates together. It should be appreciated that anyconfiguration of conductive and non-conductive layering, adhesives,etc., using any one or combination of lamination techniques may be usedto produce a desired laminate panel.

As discussed above, layers of a laminate panel may be electricallyconnected using a desired arrangement of vias formed through appropriatelayers in the laminate panel. FIG. 3A illustrates a cross-section of aportion of an exemplary laminate layer on which conductive traces areformed by patterning copper conductors 350 on non-conductive material325 and connected using vias between layers. The copper conductors 350may be patterned in any desired geometry and configured to form desiredcircuitry corresponding to one or more magnetic components (or portionsthereof) of a low-field MRI system and/or any supporting electronics,control electronics, etc. Copper conductors on different layers may beelectrically connected using vias such as plated through-hole vias 355.The plated through-holes may be formed by drilling holes through one ormore layers of a laminate panel and using a suitable plating techniqueto form a conductive path through the non-conductive material to connectelectrical conductors on different layers. It should be appreciated thatvias may be formed through an entire laminate panel, or may be formedthrough a subset of layers of a laminate panel, including to connectadjacent layers or multiple adjacent layers. A laminate layer of alaminate panel may contain multiple vias arranged to connect todifferent layers of the laminate panel. For example, a layer havingmultiple components or portions of multiple components can beelectrically isolated from each other and independently connected toconductors patterned on other layers as appropriate. The conductorspatterned on layers of a laminate panel may be connected in any waydesired, and one or more layers may not include vias at all andtherefore remain electrically isolated from other layers of the laminatepanel.

The inventors have appreciated that though copper has properties thatmake it an attractive choice for an electrical conductor, aluminum mayalso be used, either as an alternative or in combination with otherconductors such as copper to pattern one or more magnetic components (orportions thereof) on layers of a laminate panel. Aluminum weighs lessand is less expensive than copper, thus facilitating the ability tofabricate a lighter weight, reduced cost laminate panel, according tosome embodiments. FIG. 3B illustrates a cross-section of a portion of alaminate layer on which a conductive pattern is formed using aluminumconductors 370. Aluminum conductors 370 may be formed using the samelaminate techniques described herein. Aluminum has a lower conductivityas compared to copper such that aluminum conductors 370 generally needto be formed with greater thickness than copper conductors 350 to obtainthe same conductivity (e.g., an 80 mil aluminum layer may be needed inplace of a 50 mil copper layer to achieve similar performance).

FIG. 3B further illustrates another method of providing vias betweenlayers of a laminate panel using press-in pins. In particular, aluminumpin via 377 may be inserted through a hole drilled between layers of alaminate panel. It should be appreciated that pin vias may be used toconnect adjacent layers or multiple adjacent layers, including providingpin vias through an entire laminate panel. Similarly, pin vias may beused in any number and configuration desired to electrically connect theconductors patterned on the various layers of a given laminate panel.Though pin via 377 is shown in FIG. 3B in connection with the use of analuminum conductor, it should be appreciated that pin vias may beutilized and formed from any suitable conductor. It should be furtherappreciated that a laminate panel may be fabricated using a combinationof conductors such that one or more components or portions thereof areformed using a first conductor (e.g., copper) and one or more componentsor portions thereof are formed using a second conductor (e.g.,aluminum). Also, though copper and aluminum are illustrated in FIGS. 3Aand 3B, any suitable conductor may be used to pattern desired magneticand/or electrical components of a low-field MRI system, as thetechniques described herein are not limited for use with any particularconductor or combination of conductors.

It should be appreciated that laminate techniques are relatively preciseand accurate, with certain processes capable of yielding precision andaccuracy at the mil, micron or even sub-micron level. As such, usinglaminate techniques to fabricate one or more magnetic components (orportions thereof) may reduce or eliminate much of the complexity anddifficulty in manufacturing, aligning and installing magnetic componentsinvolved when using conventional techniques. Thus, using any suitableone or combination of subtractive, additive and/or semi-additiveapproaches, conductive layer(s) 212 may be patterned to form one or moremagnetic components of a low field MRI system (e.g., one or more coilsof a B₀ magnetic component, or desired portions thereof, one or moregradient coils, one or more transmit/receive coils, one or more shimcoils, one or more shielding layers, etc.) to provide a simpler, moreflexible, reliable and scalable mode of producing magnetic componentsfor MRI, some specific examples of which are illustrated in FIG. 4.Multiple low-field MRI components may be integrated on a single panel ordistributed between multiple panels to facilitate manufacture of thecomponents according to a desired configuration, as discussed in furtherdetail below.

FIG. 4 illustrates a schematic view of an exemplary multi-layer laminatepanel 400 for use with a low-field MRI system, in accordance with someembodiments. It should be appreciated that laminate panel 400 isdepicted as such to illustrate some examples of components that may befabricated via laminate techniques. However, it should be appreciatedthat a laminate panel need not include all of the components illustratedin FIG. 4, and any one or more of the illustrated components may beomitted as desired. That is, a laminate panel may include any one orcombination of the exemplary layers illustrated in FIG. 4 to form anyone or combination of components (or portions thereof) in the laminatepanel. In addition, a laminate panel may include other layers notillustrated in FIG. 4 (e.g., one or more layers for thermal management,one or more interconnect layers, one or more layers having controlelectronics or other electronic components, etc.).

The illustrated components (or any desired subset) may be formed in oneor multiple layers, and separate components may be formed on layersshared with other components, or formed on separate layers independentfrom other components. To simplify illustration of a multi-layer panel(and the nearly limitless combination of layers and configurationsthereof), the magnetic components illustrated in FIG. 4 are shownschematically without limitation on geometry of the magnetic components,or the number of layers on which they may be fabricated. As such, theexemplary layers illustrated in FIG. 4 and described herein should beunderstood to represent either a single laminate layer composed of atleast one non-conductive layer and at least one conductive layer, ormultiple such laminate layers, each composed of one or morenon-conductive layers and one or more conductive layers. Accordingly,unless otherwise specified, a layer refers to one or more laminatelayers.

It should be further appreciated that the illustrations in FIG. 4showing the various components that may be fabricated within panel 400are used to generically represent the respective component and are notintended to depict any particular geometry or configuration. Thecomponents illustrated in FIG. 4 may be patterned according to anydesired geometry and configuration, as the techniques described hereinfor integrating one or more magnetic components within a laminate panelare not limited for use with any particular geometry, configuration orarrangement. Some examples of suitable geometries that may be utilizedare discussed without limitation in further detail below.

As shown, exemplary laminate panel 400 includes a plurality of B₀ layers(410 a, 410 b) having one or more B₀ coils (411 a, 411 b) formedthereon. The B₀ coils are configured to generate at least a portion of aB₀ field for the low-field MRI system when an appropriate current isapplied to the coil(s). In some embodiments, each B₀ layer includes oneor more turns of a conductive trace patterned on the conductive layer togenerate a portion of a desired B₀ field. As shown, layer 410 a haspatterned thereon a coil 411 a, which may be patterned according to anydesired geometry. For example, coil 411 a may be patterned according toa generally circular geometry have one or more turns of conductivetraces. Coil 411 a may be electrically connected to coil 411 b patternedon layer 410 b (e.g., by a via between the layers), which also may be ofany desired geometry (e.g., a generally circular coil having one or moreturn of a conductor).

It should be appreciated that any suitable number of layers having B₀coils formed thereon may be interposed between and electricallyconnected to layers 410 a and 410 b (e.g., 1, 10, 20, 50 or more layers,etc), each having one or more respective coils formed thereon that, whenenergized with a suitable current, provides at least a portion of a B₀field configured for use in low-field MRI. It should be appreciated thateach layer may have a single coil or multiple coils, and each coil maybe patterned to have any number of turns formed thereon to achieve themagnetic and/or electric properties of a desired coil design.

The inventors have recognized and appreciated that using laminatetechniques to design and manufacture MRI components enables thefabrication of B₀ coils having arbitrary geometries and configurationsnot practicable or possible using conventional techniques formanufacturing B₀ coils for low-field MRI systems, allowing for coildesigns of virtually any geometry, configuration and/or arrangement.According to some embodiments, at least some B₀ layers on which one ormore coils, or portions thereof, are formed may be patterned usingdifferent coil geometries than other layers to achieve a desired B₀field. Some B₀ layers may have formed thereon one or more coils that canbe independently controlled to tune the B₀ field for differentapplications and environments, or to adjust the B₀ field to calibrate orotherwise achieve a B₀ field of desired strength and/or homogeneity, asdiscussed in further detail below.

The selection of a particular coil geometry or combination of coilgeometries and the arrangement and distribution of the coils within alaminate panel may depend, at least in part, on a desired B₀ field to begenerated for use with low-field MRI applications. Additionally, one ormore laminate layers having the same or different B₀ coil design may beconnected by one or more vias connecting the conductive traces on themultiple layers. In some embodiments, the locations of the vias may beselected to minimize their effect on the homogeneity of the resultant B₀field and/or to generally optimize one or more electrical properties ofthe energized coil. Non-limiting examples of B₀ coil designs that may beused to form, at least in part, a B₀ magnet for use in low-field MRI,are described in further detail below.

Because laminate techniques are capable of patterning electricalconductors with such high precision and accuracy, a B₀ magnet (or anyportion thereof) may be fabricated in laminate panel form reliably andwith high fidelity in accordance with the design specifications for aparticular B₀ magnet to achieve a B₀ field of desired strength andhomogeneity. Additionally, the ability to distribute one or more B₀coils forming a B₀ magnet (or a portion thereof) over multiple layers ofa laminate panel allows for optimizing the parameters of the B₀ magnetto generate a desired B₀ field in a manner not possible usingconventional techniques for producing a B₀ magnet. Simulations may beused to select among numerous geometries, configurations and/orarrangements (e.g., the position, geometry or other properties ofelectrical conductors on each layer contributing the B₀ field may begenerally optimized) to produce a desired B₀ field. The resulting designmay then be precisely and accurately fabricated using suitable laminatetechniques.

According to some embodiments, one or more laminate layers may includepassive magnetic component(s), such as one or more layers patterned withmagnetic materials, to facilitate the generation of a desired B₀ fieldwith reduced power requirements, or to produce a higher B₀ field usingthe same power requirements as needed without the use of magneticmaterials. For example, laminate panel 400 may include one or morelaminate layers 415 patterned with ferrous, or other magnetic materials,arranged to form a magnetic component 416 that contributes to themagnetic field generated by one or more B₀ coils to achieve a desired B₀field. Because such magnetic materials produce or tailor a magneticfield without needing a power source to provide current to produce amagnetic field, a desired B₀ field may be produced with reduced powerrequirements. Additionally, because magnetic materials can be used toproduce a higher B₀ field without a corresponding increase in powerrequirements, magnetic materials may facilitate the construction of alow-field MRI system having a higher B₀ field, potentially exceeding 0.2T (e.g., between 0.2 T and 0.5 T).

Magnetic component(s) 416 formed on one or more layers 415 may includeany one or combination of materials having relatively high magneticpermeability (μ) to assist in producing or tailoring a B₀ field ofdesired field strength and/or homogeneity. Magnetic component(s) 416 maybe formed by one or more patterned layers, provided as a sheet, or otherotherwise manufactured and incorporated within one or more laminatelayers to produce a desired magnetic field. As discussed above, the useof passive magnetic components can reduce the power requirements neededto produce a given B₀ field. That is, because a portion of a desired B₀can be produced passively (e.g., without requiring a power source tooperate the components), the burden on the active magnetic components(e.g., the one or more a desired B₀ coils) can be reduced. As a result,one or more B₀ coils can be operated with reduced current to produce, incombination with magnetic component(s) 16, a B₀ field having a desiredfield strength and/or homogeneity. Reducing the power requirements ofthe active magnetic components simplifies the cost and complexity of thepower electronics driving the magnetic components, results in acorresponding reduction in the thermal output of the laminate panel, andalso may otherwise ease the constraints on the active magneticcomponents in generating a B₀ field of desired strength and/orhomogeneity.

As discussed above, a laminate panel may further comprise at least oneconductive layer patterned to form one or more gradient coils, or aportion of one or more gradient coils, capable of producing orcontributing to magnetic fields suitable for providing spatial encodingof detected MR signals when operated in a low-field MRI system. In theexample illustrated in FIG. 4, laminate panel 400 includes a pluralityof laminate layers (420 a, 420 b, 420 c) on which gradient coils (421 a,421 b, 421 c) are formed. Layer(s) 420 a includes a conductive tracepatterned to form all or a portion of a Z-gradient coil 421 a, layer(s)420 b includes a conductive trace patterned to form all or a portion ofa Y-gradient coil 421 b, and layer(s) 420 c includes a conductive tracepatterned to form all or a portion of an X-gradient coil 421 c. Asdiscussed above, the depiction of gradient coils 421 a, 421 b and 421 cin FIG. 4 is meant to generically represent gradient coils of anysuitable geometry using any number and configuration of layers toprovide the one or more desired gradient coils.

As one non-limiting example wherein gradient coils are at leastpartially formed in a laminate panel (e.g., laminate panel 400), aZ-gradient coil may be formed, at least in part, in one or more layersusing a generally circular geometry and an X-gradient coil and aY-gradient coil may be formed, at least in part, in one or more layersusing a generally rectangular geometry such as via one or moreconductors patterned as a grid (e.g., similar to the geometryschematically illustrated in FIG. 1). The conductors for the gradientcoils may be distributed across one or multiple layers in anycombination as desired to produce integrated gradient coils, either withor without other magnetic components of a low field MRI system, andeither sharing layers with other magnetic components and/or patterned onseparate layers of a laminate panel.

In some embodiments of a laminate panel with both B₀ coils and gradientcoils for thereon, at least one layer of the laminate panel may includeboth B₀ coils (or a portion thereof) and gradient coils (or a portionthereof) that may be selectively controlled to provide desired magneticfield characteristics for low-field imaging applications. In someembodiments, at least a portion of the same conductive trace on a layerof a laminate panel may function as a B₀ coil or as a gradient coildepending on how the coil is operated. According to some embodiments, agradient coil may be distributed over multiple layers and according tosome embodiments, multiple gradient coils (or portions thereof) may beformed in a single layer (e.g., one or more of X, Y and/or Z gradientcoils), as the techniques described herein are not limited to anyparticular manner of distributing magnetic component(s) over multiplelayers of a laminate panel or multiple laminate panels. It should beappreciated that one or more gradient coils fabricated using laminatetechniques may be utilized in connection with one or more other magneticcomponents fabricated using laminate techniques (e.g., by integratingthe one or more gradient coils in a shared or separate laminate panel),or may be utilized in connection with one or more other magneticcomponents fabricated using conventional techniques as part of a lowfield MRI system.

As also discussed above, a laminate panel may further comprise at leastone conductive layer patterned to form one or more transmit and/orreceive coils, or a portion of one or more transmit and/or receivecoils, configured to stimulate MR response by producing a Bi excitationfield (transmit) and/or to receive emitted MR signals (receive) whenoperated in conjunction with the coils configured to produce a B₀ fieldand corresponding gradient fields. Such a laminate panel may incorporatesingle transmit and/or receive coils (or portions thereof) or multipletransmit and/or receive coils (or portions thereof) for performingsingle channel or parallel MRI. In the example illustrated in FIG. 4,laminate panel 400 includes layer(s) 430 on which all or a portion of atransmit/receive coil 431 is formed.

Any suitable geometry may be used to pattern the transmit/receive coilor set of transmit/receive coils. For example, in some embodiments, aspiral-shape conductor may be patterned in one or more layers to formone or more transmit/receive coil (or portions thereof). According tosome embodiments, a substantially rectangular geometry may be utilizedto fabricate one or more transmit and/or receive coils using laminatetechniques. According to some embodiments in which different coils areused for transmit and receive, transmit and receive coils may be formedin one or more layers using different respective geometries. In someembodiments, multiple layers and/or multiple laminate panels may be usedto collectively form a transmit/receive coil and/or set oftransmit/receive coils for use in a low field MRI system. It should beappreciated that one or more transmit/receive coils fabricated usinglaminate techniques may be utilized in connection with one or more othermagnetic components fabricated using laminate techniques (e.g., byintegrating the one or more other magnetic components in a shared orseparate laminate panel), or may be utilized in connection with one ormore other magnetic components fabricated using conventional techniquesas part of a low field MRI system.

A laminate panel may further comprise at least one conductive layerpatterned to form one or more electromagnetic shields arranged toprevent electromagnetic energy from the environment and/or generatedfrom components of the MRI system from disturbing the magnetic fieldsgenerated by the MRI magnetics and/or for otherwise shielding theapparatus from electromagnetic interference. In the example illustratedin FIG. 4, laminate panel 400 includes layer(s) 440 used to provideelectromagnetic shielding. Although only a single shielding layer isshown, it should be appreciated that any suitable number of shieldinglayers may be used in any different number of locations, and thepatterned conductive layer(s) forming one or more shields may be formedin separate layers or formed on layers on which other components areformed (e.g., patterned in electrical isolation on unused portions ofone or more laminate layers on which other magnetic components orportions of other magnetic portions are formed. Shielding layer(s) 440may be formed by patterning a conductor mesh in one or more layers oflaminate panel 400, though it should be appreciated that shielding maybe provided using any suitable conductor pattern to form any desiredgeometry, which geometry may be selected based on where the respectiveshielding is provided and/or characteristics of the electromagneticinterference the particular shielding is employed to suppress oreliminate.

Electromagnetic shielding may be configured to provide active shieldingor passive shielding, and embodiments are not limited in this respect.In some embodiments, shielding formed on multiple layers of a laminatepanel are connected using one or more vias. Accordingly, at least someshielding for a low field MRI system may be integrated into one or morelaminate panels in which one or more magnetic components are fabricated,either on one or more separate layers or on one or more layers on whichanother magnetic component (or portion thereof) is formed.Electromagnetic shielding may include static or dynamic shielding ofmagnetic fields, electric fields, or both.

Shim coils arranged to facilitate the production of desired magneticfields may also be patterned on one or more layers of a laminate panel.According to some embodiments, a laminate panel may comprise at leastone conductive layer patterned to form one or more shim coils, or aportion of one or more shim coils, arranged to produce or contribute tomagnetic field(s) and adapted to improve the homogeneity of the B₀ fieldgenerated by one or more B₀ coils, to otherwise improve the B₀ fieldwithin a given field of view and/or to counteract other magnetic fieldsthat negatively impact the B₀ field. In the example illustrated in FIG.4, laminate panel 400 includes layer(s) 450 on which one or more shimcoils 452 (or portions thereof) are formed. For embodiments that includea laminate panel with at least one B₀ coil and at least one shim coil,the at least one shim coil may be formed by conductive layers sharedwith (but electrically isolated from) the at least one B₀ coil (orportions thereof) or may be formed in one or more conductive layersseparate from the at least one B₀ coil (or portions thereof). As withthe other magnetic components discussed, shim coils fabricated usinglaminate techniques may be utilized with other components fabricatedusing laminate techniques (e.g., by integrating the shim coils in ashared or separate laminate panel) or utilized with other componentsmanufactured using conventional techniques as part of a low field MRIsystem.

As discussed above, multiple low-field MRI components (or portionsthereof) may be formed on a single layer (i.e., a single laminate layer)of a laminate panel. That is, multiple magnetic components or portionsof multiple magnetic components may be patterned on the same conductivelayer of a single laminate layer. For example, the conductive layer of asingle laminate layer may be patterned to form one or more B₀ coils(either forming or contributing to a complete B₀ magnet) and one or moregradient coils or portion of one or more gradient coils.

As a further example, a single laminate layer of a laminate panel may bepatterned to form all or a portion of a gradient coil and all or aportion of a transmit/receive coil. The gradient coil and thetransmit/receive coil (or portions thereof) may share at least someconductive elements formed on the laminate layer, or the gradient coiland the transmit/receive coil (or portions thereof) may be formedseparately on the same laminate layer (e.g., electrically isolated fromone another). As another example, a single laminate layer of a laminatepanel may be patterned to form all or a portion of one or more B₀ coilsand all or a portion of one or more shim coils used to tune thehomogeneity of the B₀ field for the low-field MRI system. The shimcoil(s) and the B₀ coil(s) (or portions thereof) may share at least someconductive elements formed on the laminate layer or the shim coil(s) andthe B₀ coil (or portions thereof) may be formed separately on the samelaminate layer (i.e., electrically isolated from one another). It shouldbe appreciated that any combination of components (or portions thereof)may be similarly fabricated in one or more shared laminate layers asdesired according to a specific design, as the aspects are not limitedin this respect.

The inventors have recognized and appreciated that some conductorsformed on laminate panels in accordance with some embodiments may beconfigured to perform multiple functions typically characteristic offunctions performed by separate MRI components. By repurposing the sameconductors to perform different functions and/or by sharing laminatelayers of a laminate panel between multiple components or portions ofmultiple components, the dimensions and costs associated withmanufacturing a laminate panel may be reduced.

It should be appreciated that the order of the laminate layers oflaminate panel 400 shown in FIG. 4 is provided merely for illustration,and any suitable ordering of layers may be used. That is, when multiplemagnetic components (or portions thereof) are integrated into a laminatepanel, any ordering of the laminate layers may be used to achieve adesired sequence of the integrated magnetic components. In someembodiments, the configuration of the layers and components formedthereon may be selected based, at least in part, on designconsiderations for optimizing one or more system and/or imagingparameters including, but not limited to, power consumption, gradientlinearity, B₀ field homogeneity, gradient strength, RF strength, thermalconsiderations, etc. For example, in some embodiments, one or morelayers comprising all or a portion of one or more B₀ coils may belocated as the innermost layer(s) of the laminate panel to reduce powerconsumption of the low-field MRI system. In some embodiments, one ormore outer layers of the laminate panel may be patterned to provideelectromagnetic shielding. Accordingly, any ordering of layers of alaminate panel may be used, as the techniques described herein are notlimited for use with any particular configuration in this respect.

As discussed above, though laminate panel 400 is shown as havingfabricated therein all or portions of B₀ coils, gradient coils,transmit/receive coils, shim coils, and electromagnetic shielding toillustrate exemplary components that may be fabricated using laminatetechniques, a laminate panel may include any one or combination ofcomponents, or desired portions thereof. In some embodiments, at leastsome of the exemplary components are provided separate from laminatepanel(s) (e.g., using conventional manufacturing techniques for thosecomponents). For example, some embodiments include laminate panel(s)having one or more B₀ coils formed thereon, with other components of thelow-field MRI system being provided separate from the laminate panel(s).Other embodiments include laminate panels having one or more gradientcoils formed thereon, with other components of the low-field MRI systembeing provided separate from the laminate panels. For example, in suchembodiments, the main magnetic field B₀ for the low-field MRI system maybe manufactured using conventional techniques (e.g., as described abovein connection with the bi-planar B₀ coil architecture in FIG. 1), andthe transmit/receive coil may be provided by a helmet-based and/orsurface-based coil placed around or near the object to be imaged. Inother embodiments, laminate panels may have formed thereon both one ormore B₀ coils and one or more gradient coils (or portions thereof), withother components of the low-field MRI system being produced separatefrom the laminate panel(s).

Accordingly, it should be appreciated that laminate panels manufacturedin accordance with techniques described herein may include any suitablenumber of layers on which any one or combination of low-field MRIcomponents (or portions thereof) are formed, and such laminate panel(s)may be utilized in connection with any number of other laminate panel(s)or any one or combination of other components produced using othertechniques, as the aspects are not limited in this respect. According tosome embodiments, a hybrid approach may be used wherein one or moremagnetic components are implemented with a portion being fabricatedusing laminate techniques and a portion produced using conventionaltechniques.

As discussed above, magnetic components may be fabricated, in part or infull, by distributing portions of the magnetic component(s) over aplurality of layers of a laminate panel in any number of differentconfigurations. FIG. 5 illustrates a multi-layer laminate panel 500having a B₀ coil fabricated therein, in accordance with someembodiments. FIG. 5 shows some examples of how portions of a B₀ coil maybe distributed across multiple layers of a laminate panel to produce,when energized, a magnetic field contributing to a B₀ field suitable forperforming low-field MRI. While the example layers schematicallyillustrate portions of a B₀ coil fabricated therein, each layer may (butneed not) include other components, including other magnetic components(e.g., one or more gradient coils, transmit/receive coils, shim coils,etc.), as discussed in further detail below.

Exemplary laminate panel 5 comprises fourteen laminate layers over whichportions of a B₀ magnet are distributed by patterning the respectiveconductive layers accordingly. In FIG. 5, the conductive patternsprovided on example layers are illustrated by a generally circular coil,the width of which denotes in a representative manner the number ofturns forming the respective coil. The coils are represented with solidand dashed lines to indicate that, when energized, current through coilsrepresented with solid lines flows in the opposite direction as currentthrough coils represented with dashed lines (e.g., clockwise versuscounter-clockwise, or vice versa). Example laminate panel 500 comprisescoils 510A, 510B, 510C, 510D, 510E, 510E, 510F and 510G fabricatedthereon and distributed, by way of example only, in the manner describedbelow.

Each of the exemplary layers 1-14 in FIG. 5 have fabricated thereon acoil 510A comprising a plurality of turns, for example, twenty turns ofconductive traces each. That is, as shown in the depicted layers, eachof the fourteen layers may be patterned to form a respective outer coilhaving twenty turns of conductive traces. Each coil 510A may beconnected to coil 510A in the subsequent layer using a one or more viasbetween the layers (e.g., plated through-holes, pins, or other suitableconductive vias). Alternatively, one or more of the outer coils 510A maybe electrically isolated from other coils 510A and may, for example, beconfigured to be independently energized (e.g., one or more of coils510A may be utilized as a shim coil). Each of the first six layers(e.g., Layers 1-6 illustrated in FIG. 5) consist of outer coil 510A withrespect to the integrated B₀ coil, though other components (includingother magnetic components) may be fabricated thereon in addition.

Each of layers 7-14 also have fabricated thereon a respective coil 510B,which as denoted by the dashed lines, may conduct current in an oppositedirection as coils 510A when operated. In example laminate panel 500,each coil 510B includes a number of turns less than the number of turnsin coils 510A formed on respective layers. As indicated by thedecreasing line width used to represent coils 510B, the number of turnsof conductive traces forming the respective coil may also decrease (orotherwise vary) across the layers on which the coils are distributed.For example, coils 510B in layers 7 and 8 may comprise 11 turns ofconductive traces each, coils 510B fabricated in respective layers 9-11may be formed with 10 turns, coil 510B fabricated in layer 12 may beformed with 9 turns, and coils 510B fabricated in respective layers 13and 14 may be formed with 8 turns. It should be appreciated that theturn configuration is exemplary, and that the number of turns and howthe number of turns vary (or remain constant) are not limited in anyrespect.

Each of layers 7-14 also have fabricated thereon a respective coil 510C,which as denoted by the solid lines representing the coils, may conductcurrent in the same direction as coils 510A when operated. In examplelaminate panel 500, each coil 510C includes a number of turns less thanthe number of turns forming coils 510B in the respective layer, whichnumber may vary or remain the same across laminate layers on which coils510C are patterned. For example, coils 510C fabricated in respectivelayers 7-10 may be formed with 6 turns, coil 510C fabricated in layer 11may be formed with 5 turns, and coils 510C fabricated in respectivelayers 12-14 may be formed with 4 turns. However, this arrangement ismerely exemplary and the number of turns and how they vary (or remainconstant) are not limited by this example arrangement.

Each of layers 7-11 also have fabricated thereon a respective coil 510Dand a respective coil 510E, each of layers 7-9 have fabricated thereon arespective coil 510F, and each of layers 7 and 9 have fabricated thereona respective coil 510G and a respective coil 510H. In the exampleillustrated in FIG. 5, successive coils alternate the direction in whichthey conduct current when operated, and each successive coil includes anumber of turns of conductors less than the preceding coil. However,this configuration is merely exemplary and the direction in whichcurrent is conducted, the number of turns in each coil, and the numberof coils on each layer of a laminate panel may be selected as desired toproduce or contribute to a B₀ field for low field MRI.

As discussed in connection with coil 510A, the conductors forming theexemplary coils illustrated in FIG. 5 may be connected togetherintra-layer (as discussed in further detail below) and/or connectedinter-layer using conductive vias between the layers. Furthermore, oneor more of the coils illustrated in FIG. 5 may be patterned in isolationand capable of being independently energized. In this manner, such coilsmay be used as shim coils that can be operated as needed to improve thehomogeneity of the resulting B₀ field in a given environment or undergiven loading conditions (e.g., during calibration of the low-field MRIsystem).

As discussed above, coils provided in a same laminate layer may beconfigured such that, when operated, current flows in differentdirections in different respective coils. For example, one or more coilspatterned on a given laminate layer may conduct current in the oppositedirection of one or more other coils patterned in the same laminatelayer. FIG. 6A illustrates an exemplary layer 605 of a laminate panel onwhich a B₀ coil is patterned (e.g., layer 605 may be similar to layer 12illustrated in FIG. 5). Layer 605 comprises coils 610A, 610B and 610C,each having a plurality of turns of a conductive trace (e.g., 20 turns,10 turns and 5 turns, respectively). FIG. 6B illustrates region 645indicated in FIG. 6A enlarged to show further detail regarding theconductive trace or track patterned on layer 605.

As illustrated in FIG. 6B, coils 610A, 610B and 610C are formed by asingle conductive trace 615 patterned such that when electrical currentis provided to conductive trace 615, current is conducted in alternatingcounter-clockwise and clockwise directions with respect to coils 610A,610B and 610C. In particular, coil 610A conducts current in acounter-clockwise direction, coil 610B conducts current in a clockwisedirection and coil 610C conducts current in a counter-clockwisedirection. It should be appreciated that conductive trace 615 may bepatterned to implement any desired configuration with respect to thedirection in which current is conducted. For example, layers on whichmultiple coils are fabricated may be patterned such that current isconducted in the same direction through each coil, or the direction ofcurrent conduction may be changed through one or more desired coils, astechniques described herein are not limited for use with any particularconfiguration of conductors or direction of current flow.

FIGS. 6A and 6B also illustrate exemplary vias, of which via 675 islabeled in 6B. These vias connect conductive traces patterned on onelaminate layer with conductive traces patterned on one or more otherlaminate layers (e.g., as illustrated by exemplary vias shown in FIGS.3A and 3B described above). Vias may be provided to connect conductivetraces in adjacent laminate layers and/or may be provided throughmultiple layers to connect conductive traces patterned on any number ofdesired laminate layers. Accordingly, the conductive traces patterned ondifferent layers of a laminate panel may be connected in any manner toproduce desired circuitry for magnetic components (or other electroniccomponents) fabricated within a laminate panel.

While the exemplary coils illustrated above in connection with FIGS. 5and 6 are substantially circular and have substantially uniformconcentric turns, other geometries and configurations can be utilized,as the techniques described herein are not limited for use with anyparticular geometry or configuration. For example, FIGS. 7 and 8schematically illustrate non-limiting examples of B₀ coil designs thatmay be realized using the laminate techniques described herein. UnlikeB₀ coil designs that can be practically realized for low-field MRIsystems using conventional production techniques, which typicallyinvolve winding a square or circular conductor around a rigid supportstructure, other designs may be realized by virtue of the flexibilityand precision of laminate processes. For example, conductive traces fora B₀ coil formed using laminate techniques may be fabricated andpatterned, generally speaking, according to any desired dimensions andaccording to any desired geometry. As such, the conductive paths can befabricated having relative dimensions generally not feasible usingconventional wire conductors, and can be patterned according togeometries that are not practical, if even possible, using conventionalmanufacturing techniques. As such, laminate techniques may facilitatethe manufacture of more optimal coil designs, not only for the B₀magnet, but for other magnet components as well (e.g., gradient coils,transmit/receive coils, shim coils, etc.).

Moreover, because laminate techniques allow a coil to be distributedover multiple (and in some designs relatively numerous) layers, thedimensions, position, geometry, etc. of the portion of the coil in eachgiven layer may be selected to generally optimize the resulting magneticfield. For example, the inventors have developed simulations to vary oneor more parameters of the conductive pattern on each layer to determinea generally optimal solution regarding any one or combination ofconductor dimension, position, geometry, number of turns, and/or anyother parameter(s) of the conductive pattern on each layer that impactsthe resulting magnetic field. Different MRI applications may havedifferent optimal solutions such that laminate techniques may beutilized to design and implement low-field MRI systems tailored forparticular MRI applications.

FIGS. 7A-7C illustrate spiral B₀ coil designs comprising a plurality ofturns, which may for example, be patterned on a single layer of alaminate panel or distributed over multiple laminate layers andconnected using appropriately placed vias. FIG. 7A illustrates arelatively wide spiral trace of conductive material patterned on one ormore laminate layers. FIG. 7B shows a spiral B₀ coil design wherein thewidth of the conductive path is thinner than the conductive pathillustrated in FIG. 7B, but the number of turns is greater. FIG. 7Cshows a spiral B₀ coil design having a non-uniform density of turns ofthe spiral (i.e., the spiral geometry becomes tighter as it movesinward). Using one or more variable density spiral B₀ coils may reducethe amount of power required to produce a desired strength B₀ fieldcompared to a given circular coil designs. Manufacture of such variablespiral density B₀ coils are typically impractical or not feasible usingconventional wire-wrapping techniques. It should be appreciated thatother spiral-based B₀ coil designs are also possible and the geometriesand configurations illustrated herein are merely exemplary of possiblecoil designs.

FIGS. 8A-8C illustrate concentric ring B₀ coil designs comprising aplurality of turns that may be patterned on a single laminate layer of alaminate panel or distributed over multiple laminate layers usingappropriately placed vias. FIG. 8A illustrates a plurality of connectedcircular traces of conductor material formed on one or more laminatelayers and having a uniform density with respect to the turns of theconductor. FIG. 8B shows a B₀ coil design where both the number anddensity of the turns of the B₀ coil formed on the laminate layer areincreased compared to the design of FIG. 8A, while maintaining a uniformdensity of the turns. FIG. 8C shows a B₀ coil design having anon-uniform density of turns of the concentric coils. It should beappreciated that other circular-based B₀ coil designs are also possible,for example, the exemplary B₀ coil configurations described above inconnection with FIGS. 5, 6 and 10, and embodiments are not limited inthis respect.

As discussed in connection with FIG. 4, laminate techniques may be usedto produce gradient coils integrated within a laminate panel, either inpart or in full and/or alone or in combination with one or more othermagnetic components. Gradient coils may be patterned according to anydesired geometry suitable for a particular implementation. FIGS. 9A-9Cillustrate exemplary x-gradient, y-gradient and z-gradient coils inaccordance with some embodiments. For example, FIG. 9A illustrates anexample of an x-gradient coil 920A that may be patterned on a singlelaminate layer or distributed over multiple laminate layers of alaminate panel. X-gradient coil 920A may, for example, be configured toperform frequency encoding. Similarly, y-gradient coil 920B may bepatterned on a single or multiple laminate layers and, for example, beconfigured to provide phase encoding, and z-gradient coil 920C may bepatterned on one or more laminate layers and, for example, be configuredto provide localization of image slices. However, the gradient coils maybe arranged and configured to perform any suitable spatial encoding. Itshould be appreciated that patterns illustrated in FIG. 9A-9C are merelyexemplary and any configuration or geometry may be used to implementgradient coils for a low field MRI, as the techniques described hereinare not limited to any particular design or configuration forimplementing gradient coils.

FIG. 10 illustrates an example wherein gradients coils are fabricated onat least some of the same layers as coils that form, at least in part, aB₀ magnet. In particular, FIG. 10 illustrates six laminate layers of alaminate panel wherein x-gradient coils 1020A, y-gradient coils 1020B,and z-gradient coils 1020C are patterned in the same layers as portionsof a B₀ magnet (e.g., layers having patterned thereon one or more B₀coils or portions thereof). With respect to the B₀ magnet, coils 1010Amay be similar to coils 510A illustrated in FIG. 5. The inventors haveappreciated that regions of a laminate layer in the center of such B₀coils may be utilized to pattern one or more gradient coils, or portionsthereof. For example, x-gradient coils 1020A may be patterned on layers1000A and 1000B, y-gradient coils 1020B may be patterned on layers 1000Cand 1000D, and z-gradient coils 1020C may be patterned on layers 1000Eand 1000F along with B₀ coils 1020A patterned on respective layers ofthe laminate panel. It should be appreciated that gradient coils may beintegrated in a same laminate panel with B₀ coils for a low-field MRI B₀magnet in other ways, including patterning gradient coils, in whole orin part, on at least some separate laminate layers of the laminatepanel, as integrating multiple magnetic components in a laminate panelis not limited to any particular manner of doing so. By sharing layersbetween magnetic components, the number of layers may be reduced, thusreducing the cost of manufacturing a laminate panel.

As also discussed above in connection with FIG. 4, one or more shimcoils may be fabricated within a laminate panel along with one or moreother magnetic components of a low field MRI system. FIGS. 11A and 11Billustrate example shim coils that may be patterned on one or morelayers of a laminate panel to produce a magnetic field to contribute toor assist in providing a B₀ field of desired strength and homogeneity.As one non-limiting example, shim coil 1150A may be patterned in one ormore laminate layers to produce, when energized, a correspondingmagnetic field. Coil 1150A may be configured to be independentlyenergized by, for example, electrically isolating coil 1150A from otheractive components provided within the same laminate panel or the samelaminate layer so that coil 1150A can be powered separately. Coil 1150Billustrated in FIG. 11B shows a different exemplary geometry forproviding a shim coil integrated within a laminate panel. Similar toshim coil 1150A, shim coil 1150B may be configured to be independentlyoperated.

It should be appreciated that shim coils may be provided in any mannerand configuration to contribute magnetic fields that facilitate theproduction of a B₀ field of desired strength and homogeneity. Forexample, coil 1150A and/or coil 1150B may be patterned on a single layeror distributed across multiple layers, and each coil may be patterned ona layer alone or may share one or more layers with one or more othercomponents, or portions thereof. Moreover, any number of shim coilshaving any desired geometry may be fabricated within a laminate panel,as the aspects are not limited in this respect. According to someembodiments, one or more shim coils are fabricated within a laminatepanel separate from other magnetic components of a low field MRI system.According to some embodiments, shim coils may be provided in differentgeometries and/or locations such that different combinations of shimscoils may be selectively activated in response to a given environment inwhich the system is being operated. The ability to dynamically choose acombination of shim coils to operate may facilitate the production oflow field MRI systems capable of being deployed in a transportable orcartable fashion. As discussed above, shim coils that contribute to a B₀field (e.g., to improve homogeneity), when operated, are B₀ coils sincethey in fact do contribute to the B₀ field of the MRI system.

According to some embodiments, one or more passive shims are utilized toproduce a magnetic field to contribute to a B₀ field of desired strengthand homogeneity. As discussed above in connection with FIG. 3, magneticmaterials may be utilized to produce magnetic fields without requiring asource of power to do so. Accordingly, one or more layers patterned withmagnetic materials may be provided as passive shims to assist inproducing the desired B₀ field. As with other components describedherein, passive shims may be provided in any number, arrangement andgeometry, and may be patterned on a single or multiple layers, eitheralone or on layers shared with one or more other components, as theaspect relating to providing passive shims are not limited to anyparticular configuration, geometry or arrangement. Passive shims may beprovided using separate shim elements comprised of magnetic materials ofany desired geometry. Such shim elements may be incorporated into alaminate panel by affixing the elements to the panel (e.g., using anadhesive or by other means of attachment) at desired locations and/orsuch shim elements may be arranged separate from the laminate panel atdesired locations, as the aspects are not limited to any particularmanner of incorporating one or more passive shims into a low-field MRIsystem.

As discussed in the foregoing, laminate techniques may be used toproduce magnetic component(s) in any number of different combinationsand configurations. For example, the inventors have further recognizedand appreciated that laminate panel techniques may also be used toimplement a low-field MRI system according to solenoid B₀ coil designs,wherein the B₀ field generated is oriented along the axis through thecenter of a solenoid coil, a design frequently used to implementhigh-field MRI systems. In particular, according to some embodiments,one or more solenoid-based coils may be formed on a plurality ofconnected laminate panels arranged to create a field of view through thecenter of the one or more solenoid-based coils in which an object to beimaged may be positioned.

FIG. 12 illustrates a magnetic apparatus 1200 comprising a plurality oflaminate panels having magnetic components fabricated thereon, includinga solenoid B₀ magnet for use in a low-field MRI, in accordance with someembodiments. As shown, magnet apparatus 1200 comprises eight connectedlaminate panels forming an octagonal tube in which an object to beimaged may be placed. The solenoid magnet includes a B₀ coil 1210 formedby connecting a plurality of conductive segments patterned on each ofthe laminate panels. The laminate panels may be connected in anysuitable way to ensure a stable connection between the conductivesegments formed on adjacent laminate panels (e.g., one or moreconductive adhesives, portions capable of being snapped together orotherwise attached, or any other suitable connectors may be used to makeappropriate electrical or mechanical connection between adjacentlaminate panels). When connected and energized with a suitable current,conductive segments patterned on the laminate panels form a solenoid B₀coil 1210 that generates a B₀ field in the longitudinal (Z) direction ofmagnetic apparatus 1200. It should be appreciated that the windings ofB₀ coil 1210 are schematic to illustrate how a solenoid coil can beimplemented via a plurality of laminate panels.

In the example in FIG. 12, magnetic apparatus 1200 also includesx-gradient coils 1220 a, 1220 b formed on opposing laminate panels andconfigured to generate a gradient magnetic field in the x-direction andy-gradient coils 1230 a, 1230 b formed on opposing laminate panels andconfigured to generate a gradient magnetic field in the y-direction.Additionally, magnetic apparatus 1200 also includes z-gradient coils1240 a, 1240 b having a solenoid geometry similar to B₀ coil 1210, butformed at the ends of magnetic apparatus 1200 and configured to, forexample, enable slice selection in the z-direction. The geometry andconfiguration of the gradient coils is exemplary and gradient fields maybe generated using other patterns of conductors, as the aspects are notlimited in this respect.

It should be appreciated that the laminate panels illustrated in FIG. 12represent laminate panels having any desired number of layers. That is,each laminate panel may include a single layer or each laminate panelmay comprise multiple layers, with each of the multiple layers havingformed thereon all or a portion of one or more low-field MRI components,as the desired magnetic components may be fabricated according to anydesired configuration. For example, B₀ coil 1210 may be formed by notonly connecting conductive segments on multiple laminate panels as shownin FIG. 12, but by also connecting conductive segments formed inmultiple layers of each laminate panel.

Because the laminate techniques described herein for manufacturingcomponents of a low-field MRI system are highly configurable, anydesired geometry and/or size of conductive segments may be used toprovide a magnetic apparatus according to a desired design, and theconfiguration and arrangement illustrated in FIG. 12 is provided merelyto illustrate an example in accordance with some embodiments. Forexample, laminate panels can be formed to any size and shape andconnected together to create a desired geometry. As such, a laminatepanel system may be produced that conforms to desired portions of thebody and that have patterned thereon any one or combination of magneticcomponents and/or electronic components. According to some embodiments,the techniques described in connection with FIG. 12 may be used toconstruct a laminate-based system for imaging desired anatomy, whereinany desired combination of magnetic components may be fabricated on aseries of connected laminate panels having a geometry formed around andconfigured to accommodate the desired anatomy. For example, a series ofconnected laminate panels may be constructed to image the head, asdiscussed in further detail in connection with FIGS. 22A-22C describedbelow.

As discussed in the foregoing, laminate techniques may be utilized innumerous ways to produce one or more magnetic components of a low-fieldMRI system. An exemplary low-field MRI system utilizing laminate panelsproduced using laminate techniques described herein is illustrated inFIG. 13. In particular, FIG. 13 schematically illustrates components ofa low-field MRI system 1300 in which laminate panels 1310 a, 1310 bhaving one or more magnetic components of the low-field MRI systemfabricated thereon are utilized. It should be appreciated that thebi-planar arrangement of magnetic components illustrated in FIG. 13 issimilar to that shown in FIG. 1, but with one or more magneticcomponents provided via laminate panels 1310 a, 1310 b using laminatetechniques rather than producing the magnetic components usingconventional techniques. For example, one or more magnetic componentsproduced using conventional techniques such as B₀ coils 110 a, 110 band/or gradient coils 120 a, 120 b in FIG. 1 have been replaced withintegrated magnetics in laminate panels 1310 a, 1310 b.

In the exemplary system illustrated in FIG. 13, laminate panel 1310 amay integrate one or more B₀ coils and/or one or more gradient coils toform one “side” of a bi-planar coil arrangement, and laminate panel 1310b may similarly integrate one or more B₀ coils and/or one or moregradient coils to form the other “side” of the bi-planar arrangement. Assuch, a bi-planar B₀ magnet may be produced using laminate techniquesthat, when operated, generates a B₀ field between the panels suitablefor performing low-field MRI. Gradient coils for spatially encodingemitted MR signals may also be integrated within laminate panels 1310 a,1310 b using laminate techniques. It should be appreciated from theforegoing that other magnetic and/or electronic components may befabricated within laminate panels 1310 a, 1310 b including, but notlimited to, one or more transmit/receive coils, one or more shim coils,shielding, power electronics, thermal dissipation components, etc.

As discussed above, providing integrated magnetics in laminate panelform may avoid one or more drawbacks of conventional manufacturingtechniques including, but not limited to, relatively difficult andsensitive coil winding and alignment, post-production alignment ofmagnetic components, portability, limitations on post-productionconfiguration and calibration, etc. Furthermore, providing one or moremagnetic components integrated in laminate panel form may also provideflexibility, reliability and/or scalability advantages that may simplifythe design, manufacture and installation of low field MRI systems.Integrated magnetics using laminate techniques may offer furtherbenefits including, but not limited to, flexibility of design withrespect to geometry and configuration, the ability to customizemagnetics for particular applications, reduced cost, increasedportability and/or compactness of a low field MRI system.

It should be appreciated from the foregoing discussion that laminatepanels (e.g., laminate panels 1310 a, 1310 b) may integrate any one orcombination of B₀ coils, gradient coils, transmit/receive coils, shimcoils, and electromagnetic shielding, and are not limited for use withany particular one or combination of magnetic components (or portionsthereof). Any one or more magnetic components that are not integratedtherein, may be provided using any other available techniques (e.g., oneor more magnetic components may be provided using conventionaltechniques for producing the respective magnetic component).

According to some embodiments, a magnetic component may be producedusing a hybrid technique, wherein a portion of the magnetic component isfabricated in laminate panel form and a portion of the magneticcomponent is manufactured using a different technique. For example, FIG.14A illustrates a hybrid design for a B₀ coil, in accordance with someembodiments. The hybrid design includes a coil 1405 and a laminate panel1410 having integrated therein coils 1410A, 1410B and 1410C. Coil 1405may be a wound coil as discussed above in connection with FIG. 1, or maybe one or more stacked metal plates that, when energized, produces amagnetic field that contributes to a B₀ field suitable for low fieldMRI. A coil formed by a wound conductor refers to a coil produced bywinding a conductor, such as wire, to form an electromagnet, and iscontrasted by coils produced using laminate techniques that insteadpattern the conductor to form the coil. Similarly, coils 1410A, 1410Band 1410C patterned on layers of laminate panel 1410, when energized,produce a magnetic field that contributes to a B₀ field suitable for lowfield MRI. The example hybrid design illustrated in FIG. 14A mayrepresent one side of a bi-planar design or a component or facet in anyof the geometries described herein. As such, a B₀ magnet may beconstructed using laminate and non-laminate techniques to produce adesired B₀ field suitable for performing low-field MRI.

It should be appreciated that laminate panel 1410 is illustratedschematically to be representative of any desired laminate panel havingany number of coils distributed over any number of laminate layers. Forexample, laminate panel 1410 may include one or more B0 coils (e.g., B0correction or shim coils), one or more gradient coils and/or one or moreTx/Rx coils, as the aspects are not limited in this respect. It shouldbe further appreciated that laminate panel 1410 need not be sized asshown in FIG. 14A relative to coil 1405 and may be of any size andpositioned in any manner relative to coil 1405, as the hybrid designillustrated in FIG. 14A is merely an example of how a laminate panel maybe used in conjunction with one or more coils formed using non-laminatetechniques (e.g., a wound copper coil, copper plate coil, etc.) togenerate a desired B₀ field, desired gradient field and/or desired RFfield.

FIG. 14B illustrates a portion of a hybrid magnet, in accordance withsome embodiments. Hybrid magnet 1400′ comprises a coil 1405′ configuredto produce a magnetic field that contributes to a B₀ field of a desiredfield strength and/or homogeneity. Coil 1405′ may be a coil formed by aconductor (e.g., a wound copper conductor, copper plate, etc.) providedusing a number of turns (e.g., approximately 10, 50, 100, 150, 200, 250,500 or more turns) suitable for a particular design and/or desired fieldstrength, inductance, resistance, power requirements, etc. Coil 1405′may be constructed to any desired size. For example, an exemplary coil1405′ may have an inner diameter ranging from 10 to 50 inches and anouter diameter ranging from 15 to 80 inches. It should be appreciatedthat these ranges are for illustration only and coil 1405′ may beconstructed to be larger or smaller than the above provided exemplaryranges. Coil 1405′ may be wound using ribbon wire, circular wire, squarewire or any other suitable conductor and may be of any suitable gauge.The conductor may be copper, aluminum or any suitable material, as theaspects are not limited in this respect.

Hybrid magnet 1400′ also includes laminate panel 1410′ having aplurality of laminate layers with one or more magnetic componentspatterned respectively thereon. For example, according to someembodiments, laminate panel 1410′ comprises a plurality of layers, eachhaving a B0 coil (e.g., a supplemental, correction or shim coil) orportion thereof patterned thereon that can be operated, in some casesselectively, to contribute a respective magnetic field to achieve a B₀field of desired strength and/or homogeneity. Additionally oralternately, laminate panel 1410′ may comprise a plurality of layers,each having a gradient coil or portion thereof patterned thereon toproduce a gradient magnetic field in the x, y and/or z direction.According to some embodiments, laminate panel 1410′ comprises one ormore layers patterned with an X-gradient coil, a Y-gradient coil and aZ-gradient coil, respectively, to provide gradient fields in threedimensions. Laminate panel 1410′ may also include other magneticcomponents (e.g., one or more radio frequency coils) patterned on one ormore layers, as the aspects are not limited in this respect.

It should be appreciated that laminate panel 1410′ may include any oneor combination of magnetic components and/or electronic componentsfabricated thereon using any of the techniques described herein or usingany other suitable technique. For example, laminate panel 1410′ mayinclude any of the types and combinations of magnetic componentsillustrated in FIGS. 4, 5, 9A-C, 10 and 11A-B and described in theaccompanying description. Laminate panel 1410′ may include othercomponents as well, such as electronic components, shielding, passiveelements, etc.

Laminate panel 1410′ can be of any suitable geometry and dimension. Inparticular, an exemplary square laminate panel may have dimensionsranging from 8″×8″ to 50″×50″. For example, an exemplary laminate panelmay have dimensions of approximately 16″×16″, 22″×22″ or any othersuitable dimension for a given design. Exemplary non-square panels maybe similarly dimensioned. Laminate panel 1410′ may be fabricated withany number of layers (e.g., approximately 10, 20, 30, 50 or more layers)on which any desired magnetic component may be patterned, either in fullor in part. The patterned layers may be formed from copper, aluminum orother suitable material having a thickness appropriate for the magneticcomponent(s) fabricated thereon and in view of the desired operatingcharacteristics. For example, heavy copper (e.g., 5 ounce, 6 ounce, 7ounce, 8 ounce, 10 ounce, etc.) may be used to pattern one or moremagnetic components and/or extreme copper (e.g., 20 ounce, 25 ounce, 30ounce, 50 ounce, etc.) may be used to pattern one or more magneticcomponents. However, other thicknesses of conducting material may beused, as the aspects are not limited in this respect. The totalthickness of the laminate panel 1410′ will depend, at least in part, onthe number of layers utilized, exemplary thicknesses range from 0.1″ toseveral inches.

Hybrid magnet 1400′ may be a single-sided magnet or may be one side of abi-planar magnet. In the latter case, the other side of the hybridmagnet may similarly comprise a coil 1405′ and/or a laminate panel 1410′having one or more magnetic components patterned thereon. In someembodiments, the other side of the bi-planar magnet may not include alaminate panel. In this respect, the respective sides of a bi-planarcoil may be identical in construction or may be different (e.g., mayinclude the same or different components or number of components). Assuch, a bi-planar coil may be symmetric or asymmetric, as the aspectsare not limited in this respect. A hybrid magnet may be designed toproduce any desired field strength. For example, a hybrid magnet may beconfigured to produce a field strength of approximately 5 mT, 10 mT, 20mT, 50 mT, 100 mT, 200 mT or more.

FIG. 14C illustrates a hybrid magnet, in accordance with someembodiments. Hybrid magnet 1400″ includes a coil 1405A, which may besimilar to or the same as coil 1405′ described in connection with hybridmagnet 1400′ in FIG. 14B, and laminate panel 1410″ which may be similarto or the same as laminate panel 1410′ described in connection withhybrid magnet 1400′ in FIG. 14B. In addition, hybrid magnet 1400″includes coil 1405B, which also may be similar to or the same as coil1405′. As a result, hybrid magnet 1400′ comprises two coils 1405A and1405B that contribute magnetic fields to facilitate producing a B₀ fieldof desired strength and/or homogeneity. As illustrated in FIG. 14C, athermal management component 1430 is also provided between coils 1405Aand 1405B to remove heat from the coils and laminate panel 1410″ duringoperation. Various details of thermal management component 1430 aredescribed in a concurrently filed application.

FIG. 14D illustrates hybrid magnet 1400″ after the components have beenaffixed, attached or otherwise connected to one another. As shown,thermal management component 1430 is sandwiched between, and in thermalcontact with, coil 1405A, coil 1405B and laminate panel 1410″ to drawheat away from these components during operation. For example, a coolant(e.g., a cooling liquid or gas) may be circulated through thermalcomponent 1430 via inlet 1470A and outlet 1470B to absorb heat andtransfer it away from the magnetic components. As discussed above,hybrid magnet 1400″ may be a single-sided magnet or may be one side of abi-planar magnet. Some embodiments that utilize hybrid magnet 1400″ in abi-planar configuration are described in further detail below. Table 1illustrates an exemplary construction of a bi-planar magnet, inaccordance with some embodiments.

TABLE 1 Exemplary Hybrid Magnet Field Strength 20 mT Current 30.1 AmpsTotal Power Dissipation ~2.4 kW Inductance 251 mH Wound Coils (4)Conductor 1″ × 0.016″ ribbon wire Turns 155 Inner Diameter 25.610″ OuterDiameter 31.5″ Thickness .1″ to 8″ Insulation Mylar Printed CircuitBoard Conductor 6 oz copper weight per layer (0.00084″) Shim Coils 20layers Gradient Coils 6 layers Insulation Arlon 92ML and FR4 dielectriccores and fill layers Dimensions 16″ × 16″ Total Thickness ~.380″

It should be appreciated that the construction details listed in Table 1are merely exemplary and provided merely as illustration. A hybridmagnet may be constructed in numerous other ways to meet the designconstraints of a given application of an MRI system. It should befurther appreciated that the arrangement and geometry of the coilsand/or laminate panel is not limited to those depicted. Furthermore, themagnetic components implemented using conventional manufacturingtechniques and those implemented using laminate panel techniques are notlimited to the combinations discussed herein, as hybrid techniques maybe used to produce the magnetic components of a low-field MRI system inany combination.

The inventors have further appreciated that the ability to incorporatemagnetic components in laminate panels in any desired arrangement orcombination allows for numerous different geometries (e.g., of differentshapes and/or sizes) to be realized to facilitate developing low-fieldMRI apparatus tailored for particular MRI applications. Moreover, theinventors have recognized that producing magnetics using laminate panelsmay facilitate the manufacture of relatively low cost and/or cartable orotherwise portable low-field MRI systems. Furthermore, producingmagnetics in panel form allows for manufacture of foldable and/ordeformable MRI magnetic components, which facilitates bothportability/cartability as well as the ability to construct MRImagnetics specific for particular MRI applications or to facilitateimaging specific portions of the body, as discussed in further detailbelow. Thus, producing MRI magnetics (or portions thereof) usinglaminate panels as described herein has the ability to fundamentallychange how MRI can be used in the medical or clinical setting andrevolutionize the MRI industry with far-reaching impact, greatlyexpanding the circumstances and situations for which MRI can beutilized.

Laminate panels may be produced and arranged in a variety of geometriesto facilitate the construction of a desired low-field MRI system. Forexample, FIG. 13 illustrates laminate panels arranged in a generallybi-planar arrangement. In some embodiments, laminate panels are arrangedin different geometries, for example, to produce low-field magneticsconfigured for particular types of imaging and/or to image particularanatomy of interest. FIGS. 15A-C illustrate exemplary geometries inaccordance with some embodiments. In FIGS. 15A-C, laminate panels areillustrated schematically and it is to be understood that theillustrated laminate panels generically represent laminate panels havingany desired number of layers with any desired one or combination ofmagnetic components formed thereon in any desired arrangement. FIG. 15Aillustrates an exemplary laminate panel geometry 1500A comprising fourconnected laminate panels arranged to facilitate low-field MRI of thehead. The laminate panels are arranged and connected generally toaccommodate the head so that desired portions of the head are within thefield of view of the resulting B₀ field. The laminate panels may beconnected, attached or affixed to one another in any suitable wayincluding, but not limited to, by an adhesive, by one or moreconnectors, by one or more hinges, and/or by any combination thereof, orany other suitable method.

In geometry 1500A, one or more of the laminate panels illustratedintegrate magnetics components of a low-field MRI system in any of thevarious combinations discussed herein. For example, in oneimplementation, each of laminate panels 1510A and 1520A may comprise atleast one layer having formed thereon all or a portion of a B₀ coil usedto generate a B₀ field for a low-field MRI system. In such animplementation, the pair of panels 1510A, 1520A may be arranged in thebi-planar geometry previously described with respect to FIG. 13, andsized to provide a field of view that accommodates the head. Laminatepanels 1530A and 1540A may include one or more other components of thelow-field MRI system (e.g., one or more gradient coils, transmitreceived coils, shim coils, etc.) or themselves may include all or aportion of a B₀ coil to contribute to the generation of a desired B₀field. Adding additional B₀ coils may allow for the relaxation of thepower requirements for each B₀ coil without compromising B₀ fieldstrength or homogeneity. Alternatively, one or both of panels 1530A and1540A may not include any low-field MRI magnetic components, but may befabricated to include supporting electronics, such as power or controlelectronics, may include thermal management components, shielding and/ormay be provided for structural support.

It should be appreciated that the geometry illustrated in FIG. 15A isexemplary and other arrangements are possible. For example, the panelsmay be dimensioned to accommodate the head such that the person beingscanned faces one of the side panels (e.g., panels 1510A or 1520A).Alternatively, a further panel connected to at least one of panels1510A, 1520A, and 1530A may be included to fully or partially enclose anobject (e.g., a patient's head) to be imaged. Such a geometry providesan additional laminate panel directly opposed to panel 1540, which maybe used to form one or more low-field MRI components thereon. In someembodiments, at least one of the laminate panels may comprise or havemounted thereon a visual display that enables a person being imaged toview visual images (e.g., pictures or video). Any suitable visualdisplay including, but not limited to, a liquid crystal display, may beused for this purpose.

The general configuration illustrated in FIG. 15A can also be used inconjunction with a helmet comprising transmit/receive coils, forexample, any of various form fitting helmets having generally spiralshaped coils formed on or within the helmet to provide a Bi fieldaccording to a desired acquisition sequence and to detect MR signalsemitted in response. The laminate panels forming magnetic components ofa low-field MRI system (e.g., a B₀ magnet, gradient coils, etc.) may beconstructed to accommodate the helmet such that the wearer of the helmetcan be positioned inside the field of view of the B₀ field generatedwhen the laminate panel(s) are operated. Alternatively, laminatepanel(s) having magnetic components for generating a B₀ field andcorresponding gradient fields may be integrated with a helmet havingtransmit/receive coils (e.g., a helmet wound with appropriatetransmit/receive coils) to form the magnetics of a single generallyintegrated head scanner for low-field MRI.

FIG. 15B illustrates a further exemplary arrangement of panelsdimensioned, for example, to accommodate other anatomy. As shown,laminate panels 1510B, 1520B, 1530B and 1540B are arranged to form anopen-ended rectangular tube. The relative dimensions may be selected toallow a person to place all or a portion of an extremity or appendage(e.g., a hand, a foot, an arm, a leg, etc.) within the field of view ofthe magnetic field generated. It should be appreciated that the magneticcomponents may be fabricated in laminate panel form using any one orcombination of configurations discussed herein. Furthermore, thelaminate panels in FIG. 15B may be dimensioned to accommodate anydesired anatomy (or other object), including increasing the size of thepanels and relative dimensions to accommodate the torso or whole body ofa person being imaged. It should be further appreciated that laminatepanels fabricated with one or more magnetic components may be arrangedin other configurations and geometries to produce, at least in part, adesired general purpose low-field MRI system, or a system configured forimaging particular objects or anatomy and/or to facilitate particularimaging applications, as discussed in further detail below.

FIG. 15C illustrates a planar configuration, in accordance with someembodiments. In particular, planar geometry 1500C illustrated in FIG.15C may be realized by a single laminate panel 1510C having formedthereon one or more magnetic components for producing a B₀ fieldsuitable for low-field imaging of objects placed proximate laminatepanel 1510C. Planar geometry 1500C facilitates, for example, performinglow-field MRI in circumstances wherein the object being imaged cannot beconveniently placed within or between multiple panels and/or wheremultiple panel geometries are otherwise inconvenient or unnecessary, ora further reduced cost solution is desirable. Laminate panel 1510C maybe sized as appropriate to produce a generally hand-held device that canbe held proximate an object being imaged (e.g., near a particularportion of the anatomy for which low-field MRI is desired).Alternatively, laminate panel 1510C may be sized so that a patientstands or sits next to the laminate panel to perform low-field MRI. Itshould be appreciated that laminate panel 1510C may be produced in anydesired size and/or shape to produce a planar geometry device forparticular imaging applications (e.g., tailored for imaging particularanatomy or portions of anatomy), as the aspects are not limited in thisrespect.

The techniques described herein may be used to produce magneticcomponents for a low-field magnetic resonance system configured togenerate a B₀ field of a given field strength (e.g., a field strength ofless than or equal to approximately 0.2 T, less than or equal toapproximately 0.1 T, less than or equal to approximately 50 mT, lessthan or equal to approximately 20 mT, less than or equal toapproximately 10 mT, etc). In some embodiments (e.g., embodiments thatinclude ferromagnetic augmentation to increase field strength), the B₀field of the low-field MRI system could potentially exceed 0.2 T.

As discussed above, the inventors have recognized that laminatetechniques may be utilized to produce magnetics for low-field MRIsystems. To describe additional aspects, further detail is provided inconnection with an exemplary low-field MRI system. Briefly, referringback to FIG. 13, low-field MRI system 1300 further illustrates a numberof other components that operate in conjunction with the magneticapparatus to facilitate low-field MRI. In particular, exemplarylow-field MRI system 1300 also comprises console 1330, which may includeone or more processors programmed to generate MRI pulse sequences usedto acquire data using low-field MRI system 1300 and/or console 1330 maybe configured to perform any other suitable operation. In someembodiments, console 1330 may be configured to receive MR data detectedby one or more receive coils (which may be integrated within laminatepanels 1310 a, 1310 b, or provided in a different manner such as via ahelmet worn by the user, as discussed in further detail below) andprovide the received MR data to workstation 1360 for processing the data(e.g., to reconstruct one or more MRI images). Low-field MRI system 1300also includes power management system 1340, which includes electronicsto provide operating power to one or more components of the MRI system.For example, as discussed in more detail below, power management system1340 may include one or more power supplies, gradient power amplifiers,transmit coil amplifiers, and/or any other suitable power electronicsneeded to provide suitable operating power to energize and operatecomponents of the system (e.g., power supplies needed to provideappropriate current to magnetic components integrated within laminate1310 a,1310 b).

Additionally, low-field MRI system 1300 may also include thermalmanagement system 1350 configured to facilitate the transfer of thermalenergy generated by one or more components of the MRI system away fromthose components. In some embodiments, thermal management system 1350may include components that are integrated with laminate panels 1310 a,1310 b. For example, laminate panels 1310 a, 1310 b may include one ormore laminate layers configured to dissipate heat, for example, usingany of various heat sinks, etc. Adhesives used in the fabrication oflaminate layers may be selected to have thermal absorption and/ordissipation properties to assist with management of heat generated bymagnetic components. Thermal management system 1350 may include, withoutlimitation, thermal management components to perform water-based orair-based cooling, which may be integrated with or arranged in closeproximity to MRI components that generate heat including, but notlimited to, B₀ coils, gradient coils, and/or transmit/receive coils.Components of thermal management system 1350 may include any suitableheat transfer medium including, but not limited to, air and water, totransfer heat away from components of the low-field MRI system.

FIG. 16 shows a schematic block diagram that expands on the systemdiagram shown in FIG. 13 by providing more detail on exemplarycomponents of a low-field MRI system 1300, in accordance with someembodiments. System 1300 includes MR console 1330 having controlelectronics to send instructions to and receive information from powermanagement system 1340. MR console 1330 is configured to receive orprogrammed to implement one or more pulse sequences 1610, which are usedto determine the instructions sent to power management system 1340 tooperate the coils in a desired sequence. MR console 1330 also interactswith workstation 1360 programmed to perform data acquisition and/orimage reconstruction based on received MR data. Console 1330 may provideinformation about one or more pulse sequences 1610 to workstation 1360to facilitate a data acquisition and/or image reconstruction process. Auser may interact with console 1330 via user interface 1612. Anysuitable user interface may be used, and embodiments are not limited inthis respect.

Power management system 1340 includes electronics to provide operatingpower to magnetic components 1310 of the low-field MRI system 1300 andelectronics to amplify MR signals received from magnetics components1310. The shading of the components in power management system 1340represents whether the component has generally lower-power requirements(light shading) or generally higher-power requirements (dark shading).As shown, power management system 1340 includes radio-frequency (RF)receive (Rx) pre-amplifiers, which amplify MR signals detected by one ormore RF receive coils (e.g., RF Rx coil 1640). Power management system1340 also includes RF power amplifier 1622 configured to provide poweramplification to one or more RF transmit coils (e.g., RF Tx coil 1640).

As shown, power management system 1340 also includes gradient poweramplifiers 1624 configured to drive one or more gradient coils 1642. Asdiscussed above, MRI systems often include three sets of gradient coilsarranged to provide MR gradients in three substantially orthogonaldirections (X, Y, Z). Accordingly, in embodiments that use three setsgradient coils 1642, gradient power amplifiers 1624 may comprise threegradient power amplifiers, each to drive a respective one of the sets ofgradient coils. Any suitable gradient power amplifiers 1624 may be used.In some embodiments, gradient power amplifiers 1624 may be a unipolar,pulsed gradient amplifier, however, any suitable gradient amplifier maybe used. Power management system 1340 also includes magnet power supply1626 configured to drive one or more B₀ coils (e.g., B₀ magnet 1650) toproduce the main magnetic field for the low-field MRI system. In someembodiments, magnet power supply 1626 is a unipolar, continuous wave(CW) power supply, however, any suitable power supply may be used. Powermanagement system 1340 may also include shim amplifiers 1628 arranged toindependently operate shim coils 1644.

Low-field MRI system 1300 may also include a plurality of interfacecomponents interposed between power management system 1340 and magnetics1310 including transmit/receive (Tx/Rx) switch 1630, and feed-throughfilters 1632 and 1634, which may be of any suitable design and/or type.Any suitable components may be used for these interface components, andembodiments are not limited in this respect.

As shown, magnetics 1310 includes RF Tx/Rx coils 1640, gradient coils1642, and B₀ magnet 1650. As discussed above, one or more of thesemagnetics components may be formed on one or more layers of a laminatepanel using the laminate techniques described herein. Although notshown, magnetics 1310 may have incorporated therewith electromagneticshielding configured to reduce electromagnetic interference fromadversely affecting the operation of the MRI system. Any suitableshielding may be used including, but not limited to, using one or moreshielding layers of a laminate panel, as described above.

Low-field MRI system 1300 also may include thermal management system1350 configured to provide cooling for components of the system. In someembodiments, at least a portion of thermal management system 1350 may beintegrated with one or more magnetics components 1310 formed on layer(s)of laminate panel(s), as discussed above. Thermal management system 1350may include any suitable components including, but not limited to,gas-cooled (e.g., air-cooled) systems, liquid-cooled (e.g.,water-cooled) systems, one or more fans, thermal adhesive or othersubstances used to manufacture laminate panels or other components ofsystem 1300, etc. As shown, thermal management system 1350 is configuredto manage thermal cooling of gradient coils 1642, B₀ magnet 1650,gradient power amplifiers 1624, and magnet power supply 1626. In someembodiments, one or more of these components may have at least a portionof thermal management system 1350 integrated with the component.Additionally, thermal management system 1350 may be configured toprovide thermal management functions for components other than theillustrated components shown in FIG. 16, as thermal management system1350 may be configured to provide thermal management as needed.

FIG. 17 illustrates a thermal management component, in accordance withsome embodiments. Thermal management component 1700 may be suitable fortransferring heat out and away from components of a low-field MRIsystem, for example, by dissipating heat generated by exemplary laminatepanels 1310 a, 1310 b. Thermal management component 1700 comprises acopper tube or pipe 1710 configured in a spiral shape and affixed to aspiral shaped aluminum cold plate 1720. According to some embodiments,thermal management component 1700 is designed to be positioned tothermally couple to one or more laminate panels to transfer heat awayfrom the laminate panel(s) during operation. According to someembodiments, copper tube 1710 is configured to connect to a source ofwater at either end 1710A or 1710B and deposit water via the other.Water (or any other fluid) running through copper tube 1710 absorbs heatfrom the one or components to which it is thermally coupled and carriesit away to be deposited elsewhere.

The inventors have appreciated that the spiral shape of copper tube 1710mitigates or eliminates eddy currents that often degrade the ability ofconventional thermal management components to remove heat from a system.Due to its spiral shape, thermal management component 1700 may beparticularly well-suited for removing heat from components that includetime varying magnetic fields, such as those present in magneticcomponents of an MRI system. However, thermal management component 1700may be utilized in connection with other types of components, as thespiral shaped geometry is not limited for use with any particularcomponent.

It should be appreciated that thermal management component 1700 also isnot limited for use with water, but can be used in conjunction with anyfluid, including fluids in liquid or gas state, capable of absorbing andtransporting heat. However, the ability to utilize water may facilitatedeployment of a generally portable or “cartable” low-field MRI systemhaving a thermal management component that can be connected to andutilize available water sources (e.g., any of the numerous cold waterhook-ups available not only throughout medical facilities, but at smallclinics, mobile facilities and elsewhere). Nevertheless, other coolingfluids such as liquid nitrogen, outgassing of solid carbon dioxide,refrigerated and compressed air, etc., may also be utilized by thermalmanagement component 1700, as the aspects are not limited in thisrespect.

FIG. 18 shows a more detailed block diagram of an RF signal chainincluding MR console 1330, RF Rx low noise amplifiers (LNAs) 1620, RFpower amplifier 1622, Tx/Rx switch 1630, and RF Tx/Rx coils 1640 thatmay be used in accordance with some embodiments. In a first path shownat the top of FIG. 18, control instructions from the console aretransmitted to power amplifier 1622. In some embodiments, poweramplifier 1622 may be configured to have a power output of at least twowatts. The output of power amplifier 1622 is sent to lowpass filter1812. Lowpass filter 1812 may have any desired cutoff frequency (e.g.,three MHz) to achieve the desired filtering. When Tx/Rx switch is set tothe transmit (Tx) position, the filtered power output is provided to Txcoil 1640 to produce RF excitations.

During a receive operation, Tx/Rx switch 1630 switches to the receive(Rx) position, and RF signals detected by Rx coil 1640 are provided tolow-noise amplifier (LNA) 1820, which amplifies the signals prior tofiltering by bandpass filter 1822. Any suitable bandpass filter 1822 maybe used. Following filtering by bandpass filter 1822, the filtered RFsignals are further amplified by driver 1824, followed by additionalbandpass filtering by filter 1826. The output of bandpass filter 1826 isprovided to the console for further processing including, but notlimited to, sending the amplified and filtered RF signals to workstation1360 for data processing and image reconstruction. In some cases filters1822 and 1826 may be low pass filters, high pass filters, or include aseries of filters such as a low pass, high pass, and a notch, or anycombination thereof. It should be appreciated that the RF signal chainillustrated in FIG. 18, and discussed above is merely one implementationof an RF signal chain that may be used with embodiments, and thetechniques described herein are not limited for use with any particularRF signal chain or any particular implementation in this respect.

As discussed above, the inventors have recognized that characteristicsof low-field MRI facilitate the implementation of substantially smallerinstallations that can be deployed in virtually any facility, andfurther allow for the development of portable or cartable low-field MRIsystems, some embodiments of which are discussed in further detailbelow. Because such systems may be operating in different environmentsat different times, it may be advantageous to provide “in-field” and/ordynamic calibration of one or more components of the MRI system toadjust or optimize one or more magnetic fields for particular imagingapplication in the environment in which the MRI system is operating.

Calibration of a B₀ field of an MRI system can be accomplished, at leastin part, by using shim coils, which can be adjusted to influence thehomogeneity of the B₀ field produced by the main field coil. In someembodiments that include shim coils, calibration of the B₀ field may beperformed in a similar manner by selectively activating shim coils toimprove the homogeneity of the B₀ field. According to some embodiments,one or more sensors are used to determine system characteristics (e.g.,homogeneity of a magnetic field, stability of the system) and/orcharacteristics of environmental noise, and the information from thesensors may be provided to the console, which can, in turn, tune themagnetic field by adjusting the operating parameters of the magnetics.

The inventors have recognized and appreciated that aspects of dynamiccalibration are facilitated by the use of magnetics componentsmanufactured in accordance with the laminate techniques describedherein. In some embodiments, all or a portion of one or more magneticcomponents may be individually-controllable to enable tuning of magneticfields prior to or during operation of the MRI system. For example, oneor more layers of a laminate panel may have patterned thereon aplurality of shim coils that can be individually and independentlycontrolled. The plurality of shim coils may be distributed in locationand geometry such that the plurality of shim coils can be selectivelyoperated to contribute to the B₀ field to achieve desired field strengthand homogeneity for the particular environment and loading conditions inwhich the MRI system is operating. For example, in a given environment,the B₀ field resulting from the operation of the B₀ magnet may beevaluated and the plurality of shim coils selectively operated tocontribute in such a way as to produce a suitable B₀ field in the givenenvironment. According to some embodiments, measurement of a B₀ fieldand the subsequent selection of appropriate shim coils is performed byan automated process programmed to identify a generally optimalcombination of shim coils to produce a B₀ field of desired strength andhomogeneity in a given environment and/or under given loadingconditions.

Other aspects of a low-field MRI system may also be tuned to address thecharacteristics of a particular environment. For example, in low fieldMRI, the AM frequency broadcast band (e.g., the band around 1000 kHz)may provide a source of interference for the transmit/receive coils. Toaddress this noise source, the particular frequency bands of interestmay be evaluated for activity and the magnetic components of the systemtuned to operate such that detected interference is avoided to theextent possible. For example, the field strength of the B₀ field may beincreased or decreased as appropriate so that the transmit/receive coilsoperate in a frequency band satisfactorily free from interference. Thatis, the system may be configured to detect noise and tune or configureone or more magnetic components of the MRI system to produce a desiredmagnetic field that reduces the impact of environmental noise. Forexample, the system may be configured to sweep through theelectro-magnetic spectrum in a band of interest suitable for systemoperation to locate a portion of the spectrum having the least amount ofelectromagnetic noise or interference and to tune the system to operateat a frequency in this portion of the spectrum.

According to some embodiments, noise canceling may be performed byproviding an auxiliary receive channel to detect ambient radio frequencyinterference (RFI). For example, one or more receive coils may bepositioned proximate to, but outside, the field of view of the B₀ fieldto sample the RFI but not detect MR signals emitted by an object beingimaged. The RFI sampled by the one or more auxiliary receive coils maybe subtracted off the signal received by the one or more receive coilspositioned to detect emitted MR signals. Such an arrangement has theability to dynamically handle and suppress RFI to facilitate theprovision of a generally transportable and/or cartable low field MRIsystem that likely to be subjected to different and/or varying levels ofRFI depending on the environment in which the low field MRI system isoperated.

Some embodiments may be configured to provide dynamic configuration ofthe MRI system by enabling the console to adjust the way that MRIsequences are used to generate images of a desired quality andresolution. Conventional MRI consoles typically operate by having a userselect a pre-programmed MRI pulse sequence, which is then used toacquire MR data that is processed to reconstruct one or more images. Aphysician may then interpret the resulting one or more images. Theinventors have recognized and appreciated that operating MRI systemsusing pre-programmed MRI pulse sequences may not be effective atproducing an image of a desired quality. Accordingly, in someembodiments, a user may prescribe the type of image to acquire, and theconsole may be tasked with deciding on the initial imaging parameters,optionally updating the parameters as the scan progresses to provide thedesired type of image based on analyzing the MR data received.Dynamically adjusting imaging parameters based on computational feedbackfacilitates the development of a “push-button” MRI system, where a usercan select a desired image or application, and the MRI system can decideon a set of imaging parameters used to acquire the desired image, whichmay be dynamically optimized based on MR data obtained duringacquisition.

According to some embodiments, a low-field MRI system may include fieldsensors arranged to obtain local magnetic field measurements inconnection with magnetic fields generated by a low-field MRI systemand/or magnetic fields in the environment. These magnetic fieldmeasurements may be used to dynamically adjust various properties,characteristics and/or parameters of the low-field MRI system to improvethe performance of the system. For example, a network of spatiallydistributed field sensors may be arranged at known locations in space toenable real-time characterization of magnetic fields generated by alow-field MRI system. The network of sensors are capable of measuringlocal magnetic fields of the low-field MRI system to provide informationthat facilitates any number of adjustments or modifications to thesystem, some examples of which are described in further detail below.Any type of sensor that can measure magnetic fields of interest may beutilized. Such sensors can be integrated within one or more laminatepanels or may be provided separately, as concepts related to usingmagnetic field measurements are not limited to the type, number ormethod of providing the sensors.

According to some embodiments, measurements provided by a network ofsensors provides information that facilitates establishment of suitableshimming to provide a B₀ field of desired strength and homogeneity. Asdiscussed above, any desired number of shim coils of any geometry andarrangement can be integrated in a laminate panel, either alone or incombination with other magnetic components, such that differentcombinations of shim coils may be selectively operated and/or operatedat desired power levels. As such, when a low-field MRI system isoperated in a particular environment, measurements from the network offield sensors may be used to characterize the magnetic field generatedby, for example, a B₀ magnet and/or gradient coils, to determine whatcombination of shim coils should be selected for operation and/or atwhat power levels to operate selected shim coils to affect the magneticfields such that the low-field MRI system produces a B₀ field at thedesired strength and homogeneity. This capability facilitates thedeployment of generally portable, transportable and/or cartable systemsas the B₀ field can be calibrated for a given location at which thesystem is being utilized.

According to some embodiments, measurements from the network of fieldsensors may be utilized to perform dynamic shimming during operation ofthe system. For example, the network of sensors may measure magneticfields generated by a low-field MRI system during operation to provideinformation that can be used to dynamically adjust (e.g., in real-time,near real-time or otherwise in conjunction with operating the system)one or more shim coils and/or operate a different combination of shimcoils (e.g., by operating one or more additional shim coils or ceasingoperation of one or more shim coils) so that the magnetic fieldsgenerated by the low-field MRI system have or are closer to havingdesired or expected characteristics (e.g., the resulting B₀ field isproduced at or closer to desired field strength and homogeneity).Measurements from a network of field sensors may also be utilized tonotify an operator that magnetic field quality (e.g., the B₀ field,gradient fields, etc.) fails to meet a desired criteria or metric. Forexample, an operator may be alerted should the B₀ field being generatedfail to meet certain requirement regarding field strength and/orhomogeneity.

According to some embodiments, measurements from a network of sensorsmay be used to guide and/or correct reconstruction and/or processing ofMR data obtained from operating the low-field MRI scanner. Inparticular, actual spatial-temporal magnetic field patterns obtained bythe sensor network may be used as knowledge when reconstructing imagesfrom the acquired MR data. As a result, suitable images may bereconstructed even in the presence of field inhomogeneity that wouldotherwise be unsatisfactory for acquiring data and/or producing images.Accordingly, techniques for using field sensor data to assist in imagereconstruction facilitates obtaining improved images in somecircumstances and enabling the performance of low-field MRI inenvironments and/or circumstances where field strength and/orhomogeneity is degraded.

According to some embodiments, a network of field sensors may be used tomeasure and quantify system performance (e.g., eddy currents, systemdelays, timing, etc.) and/or may be used to facilitate gradient waveformdesign based on the measured local magnetic fields, etc. It should beappreciated that measurements obtained from a network of field sensorsmay be utilized in any other manner to facilitate performing low-fieldMRI, as the aspects are not limited in this respect. In generallyportable, transportable or cartable systems, the environment in whichthe MRI system is deployed may be generally unknown, unshielded andgenerally uncontrolled. As such, the ability to characterize themagnetic fields generated by a low-field MRI system given a particularenvironment (magnetic and otherwise) facilitates the ability to deploysuch systems in a wide range of environments and circumstances, allowingfor the systems to be optimized for a given environment.

As discussed above, low-field MRI facilitates the design and developmentof MRI systems that are generally not feasible in the context ofhigh-field MRI, for example, relatively low-cost, reduced footprintand/or generally portable or transportable MRI systems. FIGS. 19-22illustrate non-limiting examples of system configurations for low-fieldMRI, in accordance with some embodiments. FIG. 19A illustrates a system1900 configured such that a seated patient is positioned so thatrelevant portions of the patient's body are located within the field ofview of the B₀ magnet. Low-field MRI system 1900 represents an openbi-planar configuration in which a pair of laminate panels 1910A and1910B are mounted to a generally U-shaped frame 1940 via supportstructures 1950A and 1950B configured to hold the laminate panels inplace.

U-shaped frame 1940 also includes an adjustable seat 1935 to facilitatepositioning patients of different stature correctly within the field ofview of the laminate panels and/or to position the patient for imagingof desired portions of the patient's body. Additionally oralternatively, the laminate panels may be adjustable to facilitate theproper positioning of the patient relative to the laminate panels. Forexample, support structures 1950A and 1950B may be raised and loweredinto and out of the arms of U-shaped frame 1940. In some embodiments,the laminate panels may be connected to articulated and/or hinged armsthat enable the panels to be secured into a more compact position toimprove portability of the system. For example, the arms on which thelaminate panels are mounted may be folded down during transport, andextended up (as shown) during operation of the MRI system. Furthermore,the base of frame 1940 may include wheels or removable castors (notshown) that allow the structure to be wheeled from one location toanother.

Magnetics components formed on laminate panels 1910A and 1910B may beconnected to power electronics 1920 via one or more cables. As shown,power electronics 1910 may be provided on a cart or other transportablestructure to facilitate the portability of the low-field MRI system.Separating the power electronics from the magnetics components of thesystem may reduce the effect of noise generated by the power electronicson the magnetic fields used to image the patient. Connections for thepower electronics (and any other needed connections such as for theconsole, workstation, display, etc.) may be provided at the base offrame 1940 with the appropriate set of the connections wired up throughthe arms of frame 1940 to the support structures 1950A and 1950B tooperate the magnetic components integrated within laminate panels 1910Aand 1910B. FIG. 19B illustrates system 1900 showing a patient 1985seated within the field of view of bi-planar magnets 1915A and 1915Bcomprising the laminate panels illustrated in FIG. 19A and an outercovering or housing, which may further comprise other components such asinternal shielding, electrical connections, power and controlelectronics, etc, and which may generally provide a measure ofenvironmental protection for the laminate panels.

FIG. 20A shows a system 2000 having a reclining configuration in whichthe magnetic components formed on laminate panels 2010A and 2010B arearranged within an frame comprising a seating portion 2035 adjustablyoriented at an angle to accommodate a patient being placed between thelaminate panels in a reclined position. The reclining portion of thesystem may be adjustable to facilitate a desired positioning of thepatient between the laminate panels so that the desired portion of thepatient is located within the field of view of the magnet. Additionallyor alternatively, the laminate panels may be adjustable within enclosure2015 to provide additional flexibility in positioning the magneticsrelative to the patient. Magnetic components formed on laminate panels2010A and 2010B may be connected via one or more suitable cables topower electronics 2020, which may be mounted on a rack or housed withanother suitable transportable structure to facilitate the portabilityof the MRI system. FIGS. 20B and 20C illustrate reclining MRI system2000 from different perspectives as well as different recliningpositions for the patient.

FIGS. 21A and 21B illustrate a portable or cartable low-field MRI system2100, in accordance with some embodiments. System 2100 may includemagnetic and power components, and potentially other components (e.g.,thermal management, console, etc.), arranged together on a singlegenerally transportable and transformable structure. System 2100 may bedesigned to have at least two configurations; a configuration adaptedfor transport and storage, and a configuration adapted for operation.FIG. 21A shows system 2100 when secured for transport and/or storage andFIG. 21B shows system 2100 when transformed for operation. System 2100comprises a portion 2190A that can be slid into and retracted from aportion 2190B when transforming the system from its transportconfiguration to its operation configuration, as indicated by the arrowsshown in FIG. 21B. Portion 2190A may house power electronics 2140,console 2130 (which may comprise an interface device such as the touchpanel display illustrated in FIGS. 21A and 21B) and thermal management2150. Portion 2190A may also include other components used to operatesystem 2100 as needed.

Portion 2190B comprises magnetic components of low-field MRI system2100, including laminate panels 2110A and 2110B on which magneticcomponents are integrated in any of the combinations discussed herein.When transformed to the configuration adapted for operating the systemto perform MRI (as shown in FIG. 21B), supporting surfaces of portions2190A and 2190B provide a surface on which the patient can lie. Aslideable surface 2165 may be provided to facilitate sliding the patientinto position so that a portion of the patient to be imaged is withinthe field of view of the laminate panels providing correspondinglow-field MRI magnets. System 2100 provides for a portable compactconfiguration of a low-field MRI system that facilitates access to MRIimaging in circumstances where it conventionally is not available (e.g.,in an emergency room).

FIG. 21C illustrates an example of a convertible low field MRI system2280 that utilizes a bi-planar hybrid magnet, in accordance with someembodiments. In FIG. 21C, the convertible system is in a collapsedconfiguration convenient for transporting the system or storing thesystem when it is not in use. Convertible system 2280 includes aslide-able bed 2284 configured to support a human patient and to allowthe patient to be slid into and out from the imaging region betweenhousings 2286A and 2286B in the direction of arrows 2281. Housings 2286Aand 2286B house magnetic components for the convertible system 2280, asdiscussed in further detail below in connection with the several viewsof the convertible system 2280. According to some embodiments, themagnetic components may be produced, manufactured and arranged usingexclusively laminate techniques, exclusively traditional techniques, orusing a combination of both (e.g., using hybrid techniques describedherein).

FIG. 21D illustrates convertible system 2280 extended and with a patientpositioned on slide-able bed 2284 prior to being inserted betweenhousings 2286A and 2286B to be imaged. FIG. 21E illustrates an explodedview of housings 2286A and 2286B. According to some embodiments, each ofhousings 2286A and 2286B house a hybrid magnet coupled to a thermalmanagement component to draw heat away from the magnetic components.Specifically, each of housings 2286A and 2286B on opposing sides of theimaging region include therein B0 coils 2205 a and 2205 b, laminatepanel 2210 (2210 b of which is visible within housing 2286B in theface-up arrangement) and thermal management component 2230 providedbetween the B0 coils. The magnetic components housed in 2286A and 2286Bmay be substantially identical to form a symmetric bi-planar hybridmagnet, or the magnetic components house in 2286A and 2286B may bedifferent to form an asymmetric bi-planar hybrid magnet, as the aspectsare not limited for use with any particular design or construction of ahybrid magnet.

FIG. 21F illustrates a close-up view of a portion of a convertiblelow-field MRI system and, more particularly, a view showing a magnetassembly 2250 for housing and securing a bi-planar magnet for alow-field MRI system, in accordance with some embodiments. The magnetassembly 2250 comprises an upper housing 2286A and a lower housing 2268Bto position and align the upper and lower magnets forming a bi-planarhybrid magnet. Housing 2286A and 2286B are connected using a pluralityof pillars or posts 2290 that provide separation between magneticscomponents housed in the upper and lower housings to provide an imagingregion into which a subject may be inserted. Upper magnet 2200 a housedin upper housing 2286A comprises a pair of B0 coils and a laminate panelcomprising a number of magnetic components, such as one or more gradientcoils and/or one or more B0 correction coils (only upper B0 coil 2205 ais visible). A thermal management component 2230 is provided in thermalcontact with the magnetic components. Thermal management component 2230includes both a cooling portion adapted to draw heat away from themagnetic components to which it is coupled, and mounting portions 2232,which extend outwardly from the magnetics components to enable themagnet to be secured to the upper housing 2286A using bolts or any othersuitable type of fastener.

FIG. 21G illustrates an exploded view of the magnet assembly 2250 shownin FIG. 21F. In FIG. 21G, both upper magnet 2200 a and lower magnet 2200b are illustrated with arrows indicating the direction in which themagnets are mounted into their respect housings 2286A and 2286B. Uppermagnet 2200 a and lower magnet 2200 b may be constructed using any ofthe techniques described herein, or using other suitable techniques, andmay form a symmetric or asymmetric bi-planar magnet. In the embodimentillustrated in FIG. 21G, each magnet includes a pair of wound B0 coils2205 a and 2205 b and a laminate panel 2210 having at least one gradientcoil and at least one B0 coil (e.g., a correction or shim coil)patterned thereon. Mounting portions 2232 shown on magnets 2200 a and2200 b are arranged and configured to be secured to mounting portions2233 of the respective housing (see housing 2286A where mountingportions 2233 are visible) with bolts 2202 when the magnetic assembly isassembled. It should be appreciated that the low-field MRI systemsillustrated in FIGS. 21A-21G are merely examples of systems in which thetechniques described herein may be utilized, as laminate-based and/orhybrid techniques may be used to provide magnetic components for anytype of system, as the aspects are not limited in this respect.

FIGS. 22A-C illustrate helmets for low-field MRI configured to performbrain scans. The helmets may include a B0 magnet in a solenoid geometryabout the surface of the helmet to produce a B0 field in an axiallydirection through the head (i.e., from the top of the head to the bottomor vice versa.) The helmets may further have incorporated therein agradient system having one or more gradient coils and an Rx/Tx coilarray from excitation and detection. In the embodiment illustrated inFIG. 22A, helmet 2500 has magnetic components arranged for generallyfull clearance of the patient's face and is therefore the most open ofthe three configurations. In the embodiment illustrated in FIG. 22B,helmet 2500′ includes one or more magnetic components arranged so as toprovide partial blockage of the face (e.g., multi-channel orsingle-channel RF coil elements and/or B0 windings may need to beprovided in this area to meet particular design requirements). In theembodiment illustrated in FIG. 22C, helmet 2500″ comprises magneticcomponents arranged so that openings remain around the patent's eyes tominimize claustrophobic effects, but one or more magnetic components arehoused within helmet 2500″ in the front portion over the patient's moutharea.

According to some embodiments, the magnetic components of the helmetsillustrated in FIGS. 22A-22C are fabricated using laminate techniques.For example, the magnetic components needed to perform MRI (e.g., B0coils, gradient coils, Tx/Rx coils, etc.) may be provided via a seriesof laminate panels connected together and arranged in a geometry aboutthe head within the helmet. According to some embodiments, a helmet isconstructed at least in part using techniques for providing magneticcomponents across a plurality of laminate panels (e.g., as described inconnection with FIG. 12) to form a three-dimensional geometry about thehead. The plurality of laminate panels may have patterned thereon B0,gradient and Tx/Rx coils to form an integrated MRI helmet for headimaging. It should be appreciated that techniques for fabricatingmagnetic components over a plurality of connected laminate panels may beused to form other geometries to provide an integrated MRI system forimaging other portions of the anatomy, as the techniques describedherein are not limited in this respect.

Having thus described several aspects and embodiments of the technologyset forth in the disclosure, it is to be appreciated that variousalterations, modifications, and improvements will readily occur to thoseskilled in the art. Such alterations, modifications, and improvementsare intended to be within the spirit and scope of the technologydescribed herein. For example, those of ordinary skill in the art willreadily envision a variety of other means and/or structures forperforming the function and/or obtaining the results and/or one or moreof the advantages described herein, and each of such variations and/ormodifications is deemed to be within the scope of the embodimentsdescribed herein. Those skilled in the art will recognize, or be able toascertain using no more than routine experimentation, many equivalentsto the specific embodiments described herein. It is, therefore, to beunderstood that the foregoing embodiments are presented by way ofexample only and that, within the scope of the appended claims andequivalents thereto, inventive embodiments may be practiced otherwisethan as specifically described. In addition, any combination of two ormore features, systems, articles, materials, kits, and/or methodsdescribed herein, if such features, systems, articles, materials, kits,and/or methods are not mutually inconsistent, is included within thescope of the present disclosure.

The above-described embodiments can be implemented in any of numerousways. One or more aspects and embodiments of the present disclosureinvolving the performance of processes or methods may utilize programinstructions executable by a device (e.g., a computer, a processor, orother device) to perform, or control performance of, the processes ormethods. In this respect, various inventive concepts may be embodied asa computer readable storage medium (or multiple computer readablestorage media) (e.g., a computer memory, one or more floppy discs,compact discs, optical discs, magnetic tapes, flash memories, circuitconfigurations in Field Programmable Gate Arrays or other semiconductordevices, or other tangible computer storage medium) encoded with one ormore programs that, when executed on one or more computers or otherprocessors, perform methods that implement one or more of the variousembodiments described above. The computer readable medium or media canbe transportable, such that the program or programs stored thereon canbe loaded onto one or more different computers or other processors toimplement various ones of the aspects described above. In someembodiments, computer readable media may be non-transitory media.

The terms “program” or “software” are used herein in a generic sense torefer to any type of computer code or set of computer-executableinstructions that can be employed to program a computer or otherprocessor to implement various aspects as described above. Additionally,it should be appreciated that according to one aspect, one or morecomputer programs that when executed perform methods of the presentdisclosure need not reside on a single computer or processor, but may bedistributed in a modular fashion among a number of different computersor processors to implement various aspects of the present disclosure.

Computer-executable instructions may be in many forms, such as programmodules, executed by one or more computers or other devices. Generally,program modules include routines, programs, objects, components, datastructures, etc. that perform particular tasks or implement particularabstract data types. Typically the functionality of the program modulesmay be combined or distributed as desired in various embodiments.

Also, data structures may be stored in computer-readable media in anysuitable form. For simplicity of illustration, data structures may beshown to have fields that are related through location in the datastructure. Such relationships may likewise be achieved by assigningstorage for the fields with locations in a computer-readable medium thatconvey relationship between the fields. However, any suitable mechanismmay be used to establish a relationship between information in fields ofa data structure, including through the use of pointers, tags or othermechanisms that establish relationship between data elements.

When implemented in software, the software code can be executed on anysuitable processor or collection of processors, whether provided in asingle computer or distributed among multiple computers.

Further, it should be appreciated that a computer may be embodied in anyof a number of forms, such as a rack-mounted computer, a desktopcomputer, a laptop computer, or a tablet computer, as non-limitingexamples. Additionally, a computer may be embedded in a device notgenerally regarded as a computer but with suitable processingcapabilities, including a Personal Digital Assistant (PDA), a smartphoneor any other suitable portable or fixed electronic device.

Also, a computer may have one or more input and output devices. Thesedevices can be used, among other things, to present a user interface.Examples of output devices that can be used to provide a user interfaceinclude printers or display screens for visual presentation of outputand speakers or other sound generating devices for audible presentationof output. Examples of input devices that can be used for a userinterface include keyboards, and pointing devices, such as mice, touchpads, and digitizing tablets. As another example, a computer may receiveinput information through speech recognition or in other audibleformats.

Such computers may be interconnected by one or more networks in anysuitable form, including a local area network or a wide area network,such as an enterprise network, and intelligent network (IN) or theInternet. Such networks may be based on any suitable technology and mayoperate according to any suitable protocol and may include wirelessnetworks, wired networks or fiber optic networks.

Also, as described, some aspects may be embodied as one or more methods.The acts performed as part of the method may be ordered in any suitableway. Accordingly, embodiments may be constructed in which acts areperformed in an order different than illustrated, which may includeperforming some acts simultaneously, even though shown as sequentialacts in illustrative embodiments.

All definitions, as defined and used herein, should be understood tocontrol over dictionary definitions, definitions in documentsincorporated by reference, and/or ordinary meanings of the definedterms.

The indefinite articles “a” and “an,” as used herein in thespecification and in the claims, unless clearly indicated to thecontrary, should be understood to mean “at least one.”

The phrase “and/or,” as used herein in the specification and in theclaims, should be understood to mean “either or both” of the elements soconjoined, i.e., elements that are conjunctively present in some casesand disjunctively present in other cases. Multiple elements listed with“and/or” should be construed in the same fashion, i.e., “one or more” ofthe elements so conjoined. Other elements may optionally be presentother than the elements specifically identified by the “and/or” clause,whether related or unrelated to those elements specifically identified.Thus, as a non-limiting example, a reference to “A and/or B”, when usedin conjunction with open-ended language such as “comprising” can refer,in one embodiment, to A only (optionally including elements other thanB); in another embodiment, to B only (optionally including elementsother than A); in yet another embodiment, to both A and B (optionallyincluding other elements); etc.

As used herein in the specification and in the claims, the phrase “atleast one,” in reference to a list of one or more elements, should beunderstood to mean at least one element selected from any one or more ofthe elements in the list of elements, but not necessarily including atleast one of each and every element specifically listed within the listof elements and not excluding any combinations of elements in the listof elements. This definition also allows that elements may optionally bepresent other than the elements specifically identified within the listof elements to which the phrase “at least one” refers, whether relatedor unrelated to those elements specifically identified. Thus, as anon-limiting example, “at least one of A and B” (or, equivalently, “atleast one of A or B,” or, equivalently “at least one of A and/or B”) canrefer, in one embodiment, to at least one, optionally including morethan one, A, with no B present (and optionally including elements otherthan B); in another embodiment, to at least one, optionally includingmore than one, B, with no A present (and optionally including elementsother than A); in yet another embodiment, to at least one, optionallyincluding more than one, A, and at least one, optionally including morethan one, B (and optionally including other elements); etc.

Also, the phraseology and terminology used herein is for the purpose ofdescription and should not be regarded as limiting. The use of“including,” “comprising,” or “having,” “containing,” “involving,” andvariations thereof herein, is meant to encompass the items listedthereafter and equivalents thereof as well as additional items.

In the claims, as well as in the specification above, all transitionalphrases such as “comprising,” “including,” “carrying,” “having,”“containing,” “involving,” “holding,” “composed of,” and the like are tobe understood to be open-ended, i.e., to mean including but not limitedto. Only the transitional phrases “consisting of” and “consistingessentially of” shall be closed or semi-closed transitional phrases,respectively.

What is claimed is:
 1. A laminate panel comprising: a plurality oflaminate layers, each of the plurality of laminate layers including atleast one non-conductive layer and at least one conductive layerpatterned to form at least a portion of a magnetics component for use inmagnetic resonance imaging (MRI), the plurality of laminate layerscomprising: at least one first laminate layer having patterned thereon afirst gradient coil configured to, when operated, generate or contributeto a magnetic field to provide spatial encoding of emitted magneticresonance (MR) signals in a first direction; at least one secondlaminate layer having patterned thereon a second gradient coilconfigured to, when operated, generate or contribute to a magnetic fieldto provide spatial encoding of emitted MR signals in a second direction;and a plurality of electrical connections between the plurality oflaminate layers comprising through-hole vias provided through one ormore layers of the plurality of laminate layers of the laminate panel,wherein a location of at least one of the through-hole vias is selectedto minimize an effect on a homogeneity of a B₀ field and/or to optimizeone or more electrical properties of at least one coil when energized.2. The laminate panel of claim 1, wherein the through-hole vias areprovided through all layers of the plurality of laminate layers.
 3. Thelaminate panel of claim 1, wherein the plurality of laminate layerscomprises a top laminate layer, a bottom laminate layer, and a pluralityof intervening laminate layers, and wherein the plurality of electricalconnections comprise through-hole vias provided through the top laminatelayer, the bottom laminate layer and each of the plurality ofintervening laminate layers.
 4. The laminate panel of claim 1, furthercomprising at least one third laminate layer having patterned thereon atleast a portion of a B₀ coil configured to contribute to a B₀ fieldsuitable for use in MRI.
 5. The laminate panel of claim 1, wherein atleast one of the through-hole vias is a plated through-hole via.
 6. Thelaminate panel of claim 1, wherein at least one of the through-hole viasis a pin via.
 7. A magnetic resonance imaging system comprising: a B₀magnet configured to generate a magnetic field to contribute to a B₀magnetic field for the magnetic resonance imaging system; and at leastone laminate panel comprising a plurality of laminate layers, each ofthe plurality of laminate layers including at least one non-conductivelayer and at least one conductive layer patterned to form at least aportion of a magnetics component for use in magnetic resonance imaging(MRI), the plurality of laminate layers comprising: at least one firstlaminate layer having patterned thereon a first gradient coil configuredto, when operated, generate or contribute to a magnetic field to providespatial encoding of emitted magnetic resonance (MR) signals in a firstdirection; at least one second laminate layer having patterned thereon asecond gradient coil configured to, when operated, generate orcontribute to a magnetic field to provide spatial encoding of emitted MRsignals in a second direction; and a plurality of electrical connectionsbetween the plurality of laminate layers comprising through-hole viasprovided through one or more layers of the plurality of laminate layersof the at least one laminate panel, wherein a location of at least oneof the through-hole vias is selected to minimize an effect on ahomogeneity of a B₀ field and/or to optimize one or more electricalproperties of at least one coil when energized.
 8. The magneticresonance imaging system of claim 7, wherein the through-hole vias areprovided through all layers of the plurality of laminate layers.
 9. Themagnetic resonance imaging system of claim 7, wherein the plurality oflaminate layers comprises a top laminate layer, a bottom laminate layer,and a plurality of intervening laminate layers, and wherein theplurality of electrical connections comprises through-hole vias providedthrough the top laminate layer, the bottom laminate layer and each ofthe plurality of intervening laminate layers.
 10. The magnetic resonanceimaging system of claim 7, further comprising at least one thirdlaminate layer having patterned thereon at least a portion of a B₀ coilconfigured to contribute to the B₀ field.
 11. The magnetic resonanceimaging system of claim 7, wherein at least one of the through-hole viasis a plated through-hole via.
 12. The magnetic resonance imaging systemof claim 7, wherein at least one of the through-hole vias is a pin via.13. A method of manufacturing a laminate panel comprising a plurality oflaminate layers, each of the plurality of laminate layers including atleast one non-conductive layer and at least one conductive layerpatterned to form at least a portion of a magnetics component for use inmagnetic resonance imaging (MRI), the method comprising: patterning, onat least one first laminate layer, a first gradient coil configured to,when operated, generate or contribute to a magnetic field to providespatial encoding of emitted magnetic resonance (MR) signals in a firstdirection; patterning, on at least one second laminate layer, a secondgradient coil configured to, when operated, generate or contribute to amagnetic field to provide spatial encoding of emitted MR signals in asecond direction; and forming a plurality of electrical connectionsbetween the plurality of laminate layers comprising through-hole viasprovided through one or more layers of the plurality of laminate layersof the laminate panel, wherein a location of at least one of thethrough-hole vias is selected to minimize an effect on a homogeneity ofa B₀ field and/or to optimize one or more electrical properties of atleast one coil when energized.
 14. The method of claim 13, furthercomprising patterning, on at least one third laminate layer, at least aportion of a B₀ coil configured to contribute to a B₀ field suitable foruse in MRI.
 15. The method of claim 13, wherein forming the plurality ofelectrical connections comprises drilling through the plurality oflaminate layers to form a plurality of through-holes and plating theplurality of through-holes to form a plurality of plated through-holevias.
 16. The method of claim 13, wherein forming the plurality ofelectrical connections comprises drilling through the plurality oflaminate layers to form a plurality of through-holes and inserting pinsin the plurality of through-holes to form a plurality of pin vias. 17.The magnetic resonance imaging system of claim 7, wherein the magneticresonance imaging system is configured to generate a B₀ magnetic fieldhaving a field strength of less than or equal to 0.2 T.
 18. The laminatepanel of claim 1, wherein the plurality of electrical connectionsbetween the plurality of laminate layers consists of through-hole viasprovided through one or more layers of the plurality of laminate layersof the laminate panel.